Advanced Anatomy

Question 1

Blood supple to skeletal muscle

Answer 1

Rich blood supply and vessels interact with muscle cells and satellite cells
Microcirculation in muscle supports muscle contraction with arcades of arterioles in the perimysium giving rise to transverse terminal arterioles which penetrate the endomysium forming a capillary network
Blood from one terminal arteriole is collected into a venule and is known as a micro vascular unit MVU representing functional unit of blood flow regulation in skeletal muscle

Question 2

Structure of skeletal muscle

Answer 2

Muscle fibres is composed of many myofibrils with sarcoplasm linking them encased in the sarcolemma with satellite cells in the periphery
Many muscle fibres together bound by the endomysium form a fascicle
Many fascicles with artery’s nerves and veins separated by perimysium internally and epimysium externally make the whole muscle which is covered in deep fascia

Question 3

Describe sarcomeres

Answer 3

Two Z lines, myomesin in the centre two c proteins either side and distance between is the M line
Actin extends from z lines inwards overlapping with myosin thick fibres
Length of myosin is the A band
Length between ends of actin molecules is the H band
Length between myosin of different sarcomeres is the I band
Tropomyosin and troponin bound to actin
Nebulin extends from z band along length of the actin filament. Acts as a template for regulation of filament length
Titin extends from z disc to the M line closely associated segment with myosin and maintains central positioning in sarcomere. During relaxation also generates passive tension through elastic extension when sarcomere is stretched

Question 4

Contraction cycle cross bridge

Answer 4

Attachment- myosin head tightly bound to actin molecule of thin filament (rigor state)
Release- ATP binds to myosin head indices release of actin and muscle relaxes - without ATP can stay in state of rigor
Bending- ATP causes myosin head to bend and initiates breakdown of ATP to ADP and inorganic phosphate which remain there
Myosin head binds to new actin site and iP is released
Release increases binding affinity
Myosin generates force to straighten and in doing so performs power stroke moving 5nm shortening the sarcomere
ADP lost during this stage
Release of ADP results in reattachment of myosin head to actin filament and rigor state reestablished

Question 5

Contraction overview

Answer 5

Ach released from axon terminal of motor neurone binds to Na ligand gated channels on motor end plate
Elicits end plate potential from increased intracellular Na triggering action potential
Propagates along sarcolemma down t tubules
Triggers release of Ca from SR
Ca binds to troponin exposing myosin bonding sites by conformational change
Cross bridge cycle begins
Ca actively pumped back into SR
Tropomyosin blocks myosin bonding site again and muscle relaxes

Question 6

Muscle origin

Answer 6

Muscle fibres are of mesodermal origin with muscles of trunk and limbs also tongue and larynx derived from paraxial mesoderm which forms somites
Muscle of orbit and face, pharynx and mastication arise directly from mesoderm

Question 7

Myogenesis

Answer 7

Proliferating stage and migration stage from the dermomyotome to form myotome
Initial cells are founder cells and these determine mature muscles destinations
Joined by fusion competent myoblasts to muscle cells
Once aligned the pores form in FCM allowing invasion of FC
Expansion of pores allows cytoplasmic exchange and finally membrane fusion.
From this point myogenic differentiation begins as cells exit cell cycle and express specific markers

Question 8

Post natal growth of muscle

Answer 8

Accomplished by satellite cells mostly which are also activated in muscle damage where they proliferate and fuse to make myofibrils to regenerate tissue
Some cells undergo asymmetric cells division to renew satellite population
In foetal muscle 30% of nuclei are from satellite cells whereas in adult only 3.8% of nuclei are from satellite cells
During development and regeneration the nuclei are found centrally migrating to the periphery as sarcomeres mature

Question 9

Satellite cells

Answer 9

Located outside the sarcolemma but within basal lamina
Large nucleus to cytoplasmic ratio
Proliferate and differentiate to form terminally differentiated multinucleated myofibers
Two types - true stem cells divide asymmetrically to give one stem cell and one daughter fated to become muscle cells
Other satellites already fated to become muscle cells

Question 10

Development and migration of fibres

Answer 10

6 processes occur
Direction of muscle fibres may change from original cranial-caudal orientation with only few muscles retaining original orientation eg rectus abdominis and erector spinae
Portions of successive myotomes commonly fuse to form single composite muscle eg rectus abdominis
Myotomes may split longitudinally into two or more layers eg intercostal
Muscle may split into two or more parts eg trapezius and sternocleidomastoid
Portion of muscle or whole muscle may degenerate leaving sheet of connective tissue ie an apponeurosis
Myotome may migrate eg diaphragm, latissimus dorsi, serratus anterior
Nerve supply maintained giving us clues to the origin

Question 11

Muscle maturation

Answer 11

Occurs in childhood
Initially muscle is slow to relax but this increases to reach adult values by ten years old
Strength gains follow typical growth curve for height and weight and mass is gained before strength
Makes up 25% body bulk at birth but this increases 3.5 times in females and 5 in males by full growth.

Question 12

Muscle fibre types

Answer 12

Type I cells characterised by endurance and little force
Type IIA fast fibres recruited second
Type IIB/X recruited last fast fibres lots of force no duration

Question 13

Muscle training

Answer 13

Increasing strength increases the number of sarcomeres and therefore cross sectional area
Endurance increases delivery of oxygen to muscle and ability of cell of utilise it increasing VO2 max, CO and neuromuscular excitability
Training decreases resting HR due to overload from working harder
No overlap between strength and endurance

Strength - high force low repetition activating type II fibres
Endurance - low force high repetition activated type I fibres

Question 14

Muscle fatigue

Answer 14

Under constant contraction will eventually fatigue due to exercise induced reduction in ability of muscle to produce force or power.
May be due to many things no one consensus
K leaving cell at each activation so repeated activity can increase extra cellular K altering excitability of cell
Decreased Ca sensitivity so doesn’t bind to troponin exposing binding sites
PCr+ADP+H gives Cr+ATP. Inorganic phosphate released may cause Decrease in Ca sensitivity and release so is considered major cause of fatigue
Accumulation of lactic acid but recent studies show has little impact on force production but is easy to measure and gives good indication of anaerobic metabolism in exercise
Intense exercise reduces ATP and Ca release decreasing rate of ATP usage reducing power output
Energy available in glycogen directly correlates to fatigue and may cause decrease of Ca release so store of energy runs out

Question 15

Neural crest cells fate

Answer 15

Melanocytes
Schwann cells
Adrenal medullary cells
Dorsal root ganglion cells
Cranial nerve sensory cells
Autonomic ganglion cells

Question 16

Dermatome overlap and discrepancy

Answer 16

Can overlap except on axial lines - non adjacent spinal segments (debatable)
Peripheral nerves can overlap eg median and ulnar nerve supplying the first and middle phalanges- median 3 1/2 ulnar 1 1/2 but this not always the case
Sometimes they do not overlap eg the thenar eminence and in limbs they remain in the specified dermatome pattern.
However dermatome maps are very inconclusive there are 14 official versions very inconsistent

Question 17

Foresters tactile map

Answer 17

Tactile dermatomal areas are larger than those determined by pain and temperature
No clinical loss if only one spinal nerve is severed aside from c2
Few subjects were studied cervical dermatomes based on 2-5 patients per nerve
No documentation regarding delay between section and testing - unsure of how long between severing and test for sensation was performed possibly different every time. Other nerves may have had enough time to compensate

Question 18

Head and Campbell’s map

Answer 18

Herpes linked to specific spinal nerves
Single spinal nerve involved in infection in only 16 cases of 450 patients therefore only 16 true samples
Small sample size 1-3 cases per nerve
Not all cutaneous nerves in a single spinal nerve will be affected and hence not all will show eruptive lesions.
Not every nerve studied

Question 19

Keegan and garretts map

Answer 19

Prolapse of vertebral discs in different regions of spinal cord will vary in severity eg cervical vs lumbar
Also mixed with vertebral fractures making results different
Prolapse may affect part of posterior root the whole of a posterior root or more than one root
Can also affect roots higher or lower than affected segment
Never studied c2 and thoracic dermatomes
Subsequent study by Davis et al 1952 tried to replicate this study showed contradicting results

Question 20

Myotomes of upper limb

Answer 20

Shoulder - abduction, lateral rotation - c5
Adduction and medial rotation - c6-8
Elbow - flexion - c5,6
Extension - c7,8
Forearm - pronation - c7,8
Supination - c6
Wrist - flexion and extension - c6,7
Fingers - flexion, extension long muscles - c7,8
Hand - intrinsic muscles - c8,t1

Question 21

Root and origin of brachial plexus terminal nerves

Answer 21

Musculocutaneous - c5-7 branch of lateral cord innervates flexors at elbow: coracobrachialis, biceps and brachialis. Sensory cutaneous: skin over radial boarder of forearm
Axillary - c5,6 branch of posterior cord. Motor nerves to deltoid, teres minor muscles. Sensory to shoulder joint and cutaneous to skin over shoulder and lateral arm
Radial nerve- c5-t1 continuation of posterior cord. Motor innervation to extensors of elbow, wrist and hand. Sensory to elbow wrist and hand joints and cutaneous to skin over dorsum of hand.
Ulnar nerve - c7-t1 continuation of medial cord. Motor innervation to wrist and hand flexors and intrinsic hand muscles. Sensory to hand joints and cutaneous to skin of ulnar aspect of hand.
Median nerve- c5-t1 arises from medial and lateral cords. Motor innervation to most long flexors of forearm and thenar muscles. Sensory cutaneous to skin of elbow, wrist and radial aspect of palm of hand.

Question 22

Brachial plexus roots, trunk, divisions, cords and terminal branches

Answer 22

C5 and C6 roots join and branch dorsal scapula nerve and contribute to long thoracic - superior trunk branches subclavian and suprascapula nerves- anterior superior division branch posterior superior nerve to join posterior middle division - lateral cord branches lateral pectoral nerve - musculocutaneous nerve terminates branch contributes to median nerve with C8 and T1
C7 root contributes to long thoracic nerve - middle trunk no branches - posterior middle division sends anterior middle branch to join anterior superior division and joined by posterior superior and inferior from superior and inferior divisions respectively - posterior cord branches upper subscapular, thoracodorsal and lower subscapular nerves - radial nerve branches auxiliary
C8 and T1 join - inferior trunk - anterior inferior division branches posterior inferior branch to posterior middle division- medial cord branches medial brachial cutaneous, medial pectoral and medial anterior brachial cutaneous - branch contribute to median nerve with C5 and 6 and terminates in ulnar nerve

Question 23

Musculocutaneous nerve

Answer 23

Roots c5-7 supplies three muscles; coracobrachialis, biceps brachii and brachialis
Terminates in lateral cutaneous nerve to forearm
Upper plexus lesion results in low of elbow flexion and lateral forearm numbness can be caused by shoulder dislocations or anterior shoulder surgery

Question 24

Radial nerve

Answer 24

Roots c5-t1 is the posterior cord from posterior divisions of all three trunks
Lies posterior to auxiliary artery in Axilla
Passes posteriorly via triangular interval with profunda brachi artery
Supplies triceps brachi, anconeus and brachioradialis above elbow is a forearm extensor below elbow supplying extensor carpi radialis, and EXR brevis, extensor carpi ulnaris, extensor digiti minimus, extensor digitorum, extensor indicis, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus
Sensory effects in wrist capsule through first webspace

Question 25

Median nerve

Answer 25

Roots c6-t1 branches from medial and lateral cords No branches in upper arm Crosses brachial artery lateral to medial to medial boarder or biceps Enters antecubital fossa medial to brachial artery and biceps tendon Supplies palmaris longus, flexor carpi radialis, pronator teres, flexor digitorum superficialis and profundus I and II, flexor pollicis longus, pronator quadratus, abductor pollicis brevis, flexor pollicis brevis, opponens pollicis Passes between two heads of pronator teres and travels through carpal tunnel giving recurrent motor branches to thenar eminence supplying LOAF muscles Gives off palmar cutaneous branch 4 Cm before wrist

Question 26

Ulnar nerve

Answer 26

Roots c8 and t1 from medial cord terminal branch Stays medial in upper arm passes posterior to medial epicondyle within cubical tunnel Enters medial forearm supplying flexor carpi ulnaris and ulnar half of flexor digitorum profundus Pierces two heads of FCU travels deep to Flexor digitorum superficialis next to ulnar giving off palmar cutaneous branch Enters hand via guyons canal and divides into deep motor and superficial sensory branches palmar cutaneous supplying medial palm. Deep motor branch supplies intrinsic of hand except LOAF muscles (supplies by median) Dorsal cutaneous branch 5cm proximal to wrist supplies dorsal hand provides digital sensation to the ulnar side for half the digits

Question 27

Variations in the brachial plexus

Answer 27

C4-8 prefixed plexus 22% variance C6-T2 postfixed plexus 1% variance 5% variation in trunks 34% in divisions 18% in cords also common Occasionally nerves may vary in position relative to the axillary artery There are often inter-nerve communications in the terminal branches (20% or more)

Question 28

C4 prefixed route

Answer 28

``` C4 goes to dorsal scapula nerve (95% go directly rather than via plexus) 98% suprascapular nerve 79% musculocutaneous nerve 49% axillary nerve 16% subclavian nerve ```

Question 29

Inter-nerve communications

Answer 29

Martin-gruber anastomoses in forearm - a communicating branch median and ulnar nerve in 10-25% people and is bilateral in 40% cases. Berrettinis ramus communications seen in 40-45% people - superficial palmar communication between the median and ulnar nerve Riche-cannieu anastomoses present in 77% of people - communication between recurrent branch of median nerve and deep branch of ulnar nerve in hand.

Question 30

Muscle strength training

Answer 30

Slight dip in muscle mass first 24/48 hours post exercise due to muscle damage sustained Results in Motor learning - performance improves but no strength increase during 6-8weeks Increase strength but not size of muscle maybe due to synchronisation of motor unit firing and increased ability to recruit all available motor units or change the fibre architecture eg packing density or contractile material increases 10-12 weeks slow but steady increase in muscle size and strength by hypertrophy. Significant and prolonged activity needed to cause change in muscle structure

Question 31

Muscle performance

Answer 31

Influenced by turnover of contractile cells promoting loss of gain of mass Muscle protein synthesis enhanced for 24-48 hours post single bout of resistance training Training also increases satellite cells needed to fuse with muscle fibre to increase size of cells Greater satellite activation means greater muscle mass increase seemingly associated mostly with eccentric contraction rather than concentric.

Question 32

Role of satellite cells in hypertrophy

Answer 32

Increase in muscle protein during hypertrophy can be achieved by either increased RNA and protein synthesis from existing nuclei or increase number of nuclei and keep same level of synthesis Nuclei come from satellite cells Resistance training very effective in producing new satellite cells Satellite production exceeds muscle hypertrophy

Question 33

Endurance and muscle composition

Answer 33

Exercises increase oxygen demands of working muscle therefore the endurance of muscle depends on rate of o2 delivery and utilisation Age related changes to o2 uptake may explain decrease of endurance with age Increases satellite cells and CV and respiratory systems improve o2 delivery and cells increase o2 utilisation. Capillary density increases for greater diffusion distance of o2 improving delivery to mitochondria Mitochondria change and increase in size and number to improve o2 metabolism. Glucose uptake also enhanced as is insulin sensitivity which counteracts insulin resistance in type II diabetes Increases fatty acid metabolism leads to better preserved glucose store and increased endurance Cardiac muscle hypertrophies increasing CO and resting heart rate decreases overall results prolonging time exercise can be done for

Question 34

Enhanced mitochondria and exercise

Answer 34

After training is associated with less breakdown of high energy phosphates during submaximal exercise so less AMP and Pi accumulate lowering rate of fatigue and glycogenolysis Higher glycogen levels can also delay fatigue by preventing decrease in SR Ca release which occurs when glycogen localised in myofibrils reaches lower levels

Question 35

Overtraining.

Answer 35

May lead to chronic fatigue and loss of muscle strength Early indication may be decrease in neuromuscular excitability usually result of endurance training Estimated occurs in 30% non elite and 60% elite athletes during sporting lifetime Due to successive alterations in metabolism where main energetic stores shift from carbohydrates and lipid proteins Need to cut back in exercise

Question 36

Muscle regeneration

Answer 36

Satellite cells activated in response to physiological stimuli of exercise or pathology eg injury/disease Satellite cells are heterogenous mix of stem cells and committed myogenic progenitors Some activated cells divide asymmetrically suggesting one remains a stem cell while other differentiates May be different populations of stem cells not all of which unite with muscle fibre Cells must then make transition from proliferation to differentiation The fusion of cells produce new myofibers or fusion of cells to damaged myofibers Has central nuclei which as ages move to periphery

Question 37

Age, gender and muscle

Answer 37

Peak muscle and bone strength between 25-30 years, skeletal muscle mass decreases at 6% per decade after 30 impacting basal energy needs and max aerobic capacity. Age related effects severely reduce strength of extensor muscles of lower limb especially knee and ankle Part of this due to reduction in physical activity Loss of lower limb strength leads to increase in falls in elderly 28-35% over 65 have at least one fall per year By 90 about 30% muscle mass lost Decrease in strength equal for all groups despite continued training Life long endurance training gives high aerobic power but muscle strength is still the same Endurance limiting factor is VO2 max and after mid 20’s this slowly declines so by 70 is half of peak value Weakness and fatigue can be slowed but not stopped Muscle fibre atrophy result of individual fibre atrophy and decrease in number of fibres with preferential loss of type II Loss of muscle force suggesting dysfunctional proteins - myosin heavy chain synthesis declines with age Decreased ability to remodel muscle after injury reducing strength and endurance Decrease in use of myosin head decreasing force with age Loss of satellite cells may result in failure to maintain muscle cell fibre size may explain higher prevalence of muscle injuries and longer recovery times Increase in proportion of connective tissue increases stiffness

Question 38

Endurance and elderly

Answer 38

Enhanced muscle insulin sensitivity in everyone so useful for elderly especially preventing decline in mitochondrial respiratory capacity with age Resistance exercise gains strength and power for this too

Question 39

Gender and muscle composition

Answer 39

In adolescent girls and women relationship between muscle strength, height and weight is similar to children’s but adolescent boys there is hypertrophy of muscle probably due to increased testosterone Women show greater loss of muscle size and strength but may be reduced by use of HRT.

Question 40

All factors affecting muscle composition

Answer 40

``` Atrophy Motor units number Changes in nervous system Diet Physical activity Endocrine changes Altered enzyme activity levels Altered muscle contractility ```

Question 41

Shoulder joints

Answer 41

Acromioclavicular - gliding Joint less movement than others Scapulothoracic Sternoclavicular - physically a saddle joint but functionally a ball and socket joint Glenohumeral - ball and socket

Question 42

The glenohumeral joint

Answer 42

Ball and socket synovial joint Lax capsule to allow movement - very weak capsule hangs dependent underneath joint therefore making it very unstable Most common dislocation in body however only affects 1-2% of population Head of humerus is 3-4x larger than the glenoid fossa therefore it doesn’t sit in the joint entirely also making it unstable Stability of the joint comes from the rotator cuff muscles and ligaments Glenoid labrum helps deepen glenoid cavity by 2.5mm however is prone to damage from dislocations or from age etc. Causing tears or detachment. Also acts as anchoring point for ligaments Subscapular bursa - can also get bursa infraspinatus but not common. Blood supply from suprascapular, subscapular, anterior and posterior circumflex humeral arteries Innervated by axillary, suprascapular, lateral pectoral nerves

Question 43

Factors for glenohumeral stability

Answer 43

Glenoid fossa and humeral head mismatch size Glenoid labrum helps deepen cavity 2.5mm. Acts as chock block and attachment site for ligaments and long head of biceps. 20% of joint compression effect. Glenohumeral, coracoacromial and corcacohueral ligaments help stabilise Intra articular pressure - negative pressure creates suction between bones holding joint together. If pressure is dissipated dislocation very likely Muscles - rotator cuff (supraspinatus for abduction, teres minor, infraspinatus and subscapularis), long head of biceps and deltoid very important

Question 44

Position and shape of glenoid fossa

Answer 44

Slight angulation as scapula runs lateral and forward to meet head of humerus meaning plane of flexion and extension is offset slightly which may be beneficial for resisting anterior pressures eg pushing something A glenoid notch shape in glenoid fossa is present in 55% of patients which often gives rise to potential problems from bending the glenoid labrum making tearing or anterior detachment of the labrum more likely.

Question 45

Ligaments of glenohumeral joint

Answer 45

Superior, middle and inferior glenohumeral ligaments extend from the scapula to the head of the humerus Superior - supraglenoid tubercle to lesser tuberosity blends with coracohumeral ligament to close the rotator interval Middle - labrum or bony glenoid neck to medial to lesser tuberosity inferior to subscapularis tendon, often stretched by heavy lifting Inferior - hammock shaped important for arm abduction to cup head. Between the superior and middle protrudes the supscapular bursa Long head of biceps femoris is continuous with the glenoid labrum Coracohumeral ligament goes from the coracoid process to the humerus Transverse ligament runs above the glenohumeral ligaments over the long head of biceps attachment

Question 46

Stability of shoulder from muscles

Answer 46

Primary - rotator cuff muscles (supraspinatus, infraspinatus, subscapular and teres minor), Deltoid and long head of biceps Secondary - teres major, latissimus dorsi, pectoralis major The cuff muscles actively resist deltoid shear forces - the glenohumeral joint compression centres the humeral head making more stable Rotator cuff tendons blend into the capsule - cuff tension actively tightens glenohumeral ligaments Proprioceotion - joint position awareness and repositioning through continuous afferent input and efferent output

Question 47

Sternoclavicular joint

Answer 47

Synovial articular disc 60 degree superior inferior movement 20 degree anterior posterior movement Anterior and posterior sternoclavicular ligaments stabilise Interclavicular and costoclavicular ligaments Blood supply from clavicular branch of thoacoacromial artery and internal thoracic Nerve supply from nerve to subclavius and medial supraclavicular nerve

Question 48

Acromioclavicular joint

Answer 48

Small area of contact Synovial possible with disc Lax capsule for movement Acromioclavicular ligament Blood supply from suprascapular artery and posterior circumflex humeral and acromial branch of the thoracoacromial artery Innervation axillary, suprascapular and lateral pectoral nerve Coracoclavicular ligament formed from the trapezoid and conoid ligaments

Question 49

Purpose of the spine

Answer 49

Protect the spinal cord Provide structural support and balance upright posture Enable movement - flexion, rotation etc.

Question 50

Bony compartments of the spine

Answer 50

``` 7 cervical 12 thoracic 5 lumbar 5 sacral 4 Coccyx ``` 33 total

Question 51

Vertebrate anatomy

Answer 51

``` Body -75% of longitudinal load Foramen for nerves to travel Transverse and spinous processes Pedicle connects body to processes Lamina connects transverse to spinous processes Posterior parts support 25% load. ``` Differences between vertebrae - Cervical - three main distinguishing features: Bifid spinous process – the spinous process bifurcates at its distal end. Exceptions to this are C1 (no spinous process) and C7 (spinous process is longer than that of C2-C6 and may not bifurcate). Transverse foramina – an opening in each transverse process, through which the vertebral arteries travel to the brain. Triangular vertebral foramen Two cervical vertebrae that are unique. C1 and C2 (called the atlas and axis respectively), are specialised to allow for the movement of the head. Thoracic - medium-sized, and increase in size from superior to inferior. Their specialised function is to articulate with ribs, producing the bony thorax. Each thoracic vertebra has two -€˜demi facets,-€™ superiorly and inferiorly placed on either side of its vertebral body. The demi facets articulate with the heads of two different ribs. On the transverse processes of the thoracic vertebrae, there is a costal facet for articulation with the shaft of a single rib. For example, the head of Rib 2 articulates with the inferior demi facet of thoracic vertebra 1 (T1) and the superior demi facet of T2, while the shaft of Rib 2 articulates with the costal facets of T2. The spinous processes of thoracic vertebrae are oriented obliquely inferiorly and posteriorly. In contrast to the cervical vertebrae, the vertebral foramen of thoracic vertebrae is circular. Lumbar - large vertebral bodies, which are kidney-shaped. They lack the characteristic features of other vertebrae, with no transverse foramina, costal facets, or bifid spinous processes. However, like the cervical vertebrae, they have a triangular-shaped vertebral foramen. Their spinous processes are shorter than those of thoracic vertebrae and do not extend inferiorly below the level of the vertebral body. Their size and orientation allows for clinical access to the spinal canal and spinal cord between lumbar vertebrae (which would not be possible between thoracic vertebrae). Examples include epidural anaesthesia administration and lumbar puncture.

Question 52

Intervertebral disc anatomy

Answer 52

Annulus fibrosus outer section | Nucleus pulposus inner section

Question 53

Ligaments of the spine

Answer 53

Ligamentum flavum - runs between one vertebrate to another in the foramen Interspinous ligament - runs over the superior and inferior articulating processes Intertransverse ligaments - between transverse processes of superior and inferior vertebrae Posterior longitudinal ligament - runs whole length of spine inside foramen anterior to ligamentum flavum Anterior longitudinal ligament - runs whole length of spine on anterior body of vertebrae Supraspinous ligament - runs length of whole spine on spiney processes

Question 54

Kinematic variables

Answer 54

Type of motion occuring Location of movement Direction of movement Magnitude of motion

Question 55

Types of motion

Answer 55

Rotation Translatory - each section of limb involved moves the same distance at the same time in the same plane Curvilinear (rotators and translating) General plane motion - could be special case of curvilinear motion where object rotates about the axis while the axis is translated by motion of adjacent segment eg the forearm and hand moves in parabolic path as it rotates around elbow joint and elbow is moved by shoulder

Question 56

Location of movement

Answer 56

Frontal plane divides body into front and back Sagittal plane divides into right and left Transverse plane divides into upper and lower segments Movement takes place along three axis which are perpendicular to Plane of movement Frontal - abduction, addiction and lateral flexion Sagittal - flexion and extension Horizontal - rotation

Question 57

Uniaxial, biaxial and triaxial joint movements and gliding

Answer 57

Uniaxial joint has movement into one plane with one degree of freedom eg flexion and extension Biaxial joint has two planes of movement eg abduction and adduction as well as flexion and extension Triaxial joints/multiaxial has three degrees of freedom with third movement involved eg rotation Not all joint movements are within planes as some joints are non axial and perform gliding movements in all directions - only very small movements permitted

Question 58

Velocity of movement

Answer 58

Displacement per unit time regardless of direction Is known as speed whereas displacement per unit time in given direction is velocity Changes in velocity per unit time is acceleration Rate of movement used to know rate of acceleration or deceleration eg swinging limb in gait cycle accelerates in initial swing but decelerates before contact with ground to minimise ground reaction force

Question 59

forces affecting kinetics

Answer 59

``` External - Gravity Wind Mechanical force etc Internal - Muscles Ligaments Bones May be use to counteract external forces Both - Friction and atmospheric pressure may act as both internal and external forces ```

Question 60

Force vectors

Answer 60

All forces are vector quantities and have: A point of application on the objects being acted on An action line in direction indicating a pull towards source or push away from source A magnitude ie the quantity of force exerted Vectors are represented by an arrow with point at point of application, shaft and arrowhead in direction of force and length representing magnitude

Question 61

Centre of gravity

Answer 61

COG is a hypothetical point which all mass is concentrated and the point at which force appears to act COG is point at which the object is held in balance and the line or direction of gravity is always downwards In humans COG depends on proportions of the person and also their position. This centre and one change as the person moves For an object to be stable the line of gravity must pass within the base of support and when outside this the object will fall Larger the base of support the closer the COG to the base of support and the greater stability of the object Bipedal (humans) have small bases of support

Question 62

Reaction forces

Answer 62

Newton’s third law - forces always come in pairs Gravity exerts force and things that touch objects exert force on the object Whenever two objects are in contact they exert force in each other Internal forces generated by muscles, joint capsules, ligaments to counteract external forces like ground reaction forces in gait cycle. Muscles deemed internal moments - flexor or extensor moments opposing forces A moment is a measure of force tendency to cause the body to rotate about a specific axis For a moment to develop the force must act to cause the body to twist as a moment is due to a force not having an equal and opposite force along its line of action Newton’s first law states objects in equilibrium will remain at rest or not move unless acted upon by an unbalanced force and forces must therefore equal 0 Newton’s second law - objects in motion acceleration will be proportional to forces acting. A=F/m or F=ma Acceleration=force/mass

Question 63

Kinematic chain

Answer 63

An engineering term to describe series of segments joined together and fixed at each end, closed chain Movement of one segment causes the next and so on In humans long bones represent chains and explains why movement at one joint affects another When limbs are not fixed the chain is open which is most common limb use eg foot off the ground in walking while closed chain is when pushing against a solid object eg foot on in walking or pushing against a wall Concept is only useful when elements are fixed such as when triceps extend arm with open chain but when closed the extension of arm moves away from the body eg press up motion this is due to the closed chain pushing against a force eg a wall while the open chain has less force so moves differently

Question 64

Common shoulder condition causes

Answer 64

``` Fractured clavicle Sternoclavicular joint dislocation Acromioclavicular dislocation Glenohumeral instability Rotator cuff tears Rotator cuff tendinitis Impingement syndrome - rotator cuff muscles irritated and inflamed when passing through the subacromial space causing pain Frozen shoulder - adhesive capsulitis, painful, connective tissue of glenohumeral joint becomes inflamed and stiff restricting motion Glenohumeral arthritis ```

Question 65

Top shoulder conditions for different ages

Answer 65

31-45 - incomplete cuff lesion and frozen shoulder most common but very close Above 45 - degenerative joint disease, frozen shoulder and full thickness cuff tear most prominent not much else More female related injury in all age ranges

Question 66

Clavicle fractures and sternoclavicular and acromioclavicular dislocations

Answer 66

Clavicle fractures and dislocations very easy to spot Bones move towards the ligaments or muscles attached to them causing large displacement Fracture most common in medial third of clavicle due to being half way between ligaments either side making it weakest point Can get medial or lateral breaks more commonly the acromial side changing shape and look completely Sternoclavicular joint dislocations most commonly dislocate anteriorly, tearing ligaments. This is caused by force to lateral aspect of shoulder thrusting coracoid process back and clavicle forward. Posteriorly may be life threatening as the clavicle may compress or lacerate al lung, great vessel eg subclavian vein tearing or crushing, trachea or oesophagus all which lie behind it Usually caused by a fall or sports with force on the shoulder Acromioclavicular joint dislocation caused by downward blows to lateral shoulder or fall in outstretched arm.

Question 67

Avascular necrosis of glenohumeral joint

Answer 67

Hass’ disease - very advanced stages of avascular necrosis In radiology can see dense sclerosis over head of humerus ‘the snowcapped sign’ Caused by loss of blood supply to humeral head, axillary artery main branch gives off anterior and posterior humeral circumflex arteries and anastomoses with vessels from rotator cuffs Can be caused by lax capsule moving humerus too high in glenoid fossa not sitting correctly and muscles pulling head upwards with nothing preventing them trapping arteries etc. Resulting in necrosis

Question 68

Rotator cuff tears and glenoid labrum tears

Answer 68

Progressive thinning and weakening of muscles with age increases likelihood of potential damage to cuff during elevation of the humerus tearing the muscles Glenoid labrum can have SLAP (superior to lateral, anterior to posterior lesion) lesions on superior head of humerus associated with long head of biceps attachment and labrum can be completely torn off here. or bankart tears on underside anterior of capsule Most common cause of shoulder pain and instability leading to secondary problems

Question 69

GHJ impingement syndrome

Answer 69

Occurs when a bursae or tendon is squeezed between moving structures Supraspinatus is commonly impinged Common in sports that emphasise overhead arm movements

Question 70

Frozen shoulder

Answer 70

Adhesive capsulitis Symptomatic limitation of passive motion of shoulder Caused by thickening and stiffening of joint capsule after inflammation of rotator cuff tendons No evidence of arthritis, calcium deposits or other abnormalities seen Four types - Idiopathic - most common, unknown cause Diabetic - may be due to excess sugar in bloodstream Post traumatic stiff shoulder Post surgical stiff shoulder Previous damage caused flaring of pain Peak incidence age is 55

Question 71

Glenohumeral dislocations

Answer 71

More common to dislocate anteriorly More prone to dislocate in a 180degrees abducted arm position Taking a Y view X ray allows good diagnosis of dislocation Patient stands with back facing x ray diagonally with scapula being first bone in x ray picture and humerus furthest away from imagining

Question 72

Impingement syndrome

Answer 72

rotator cuff muscles irritated and inflamed when passing through the subacromial space causing pain Can cause development of Sesemoid bone from inflammation called subacromial roughness can be palpated or calcific tendinitis from irritations, Ca deposits build up forming solid bodies

Question 73

Acromial spur

Answer 73

Reactive changes in greater tuberosity of humerus causes acromial spur growth

Question 74

Painful arc syndrome

Answer 74

60-120 abduction is very very painful from excess compression on bursae of shoulder but once rotation at 120 degrees begins pain lessens

Question 75

The notochord

Answer 75

A cellular rod forming the primitive axis of the embryo giving it rigidity. The rod forms the mesenchymal axial skeleton and is the basis for the axial skeleton (vertebral column, Ribs, sternum and skull). The developing notochord induces the ectoderm to form the neural plate which develops into the CNS.

Question 76

Somite development week 4

Answer 76

mesoderm cells are arranged around a small cavity. The cells of the anterior and medial walls of somite lose epithelial arrangement and migrate in the direction of the notochord (sclerotome). The posterior somite gives rise to myotome layer The dermatome cells lose their epithelial configuration and spread out under the ectoderm to become the dermis.

Question 77

Sclerotome development

Answer 77

Sclerotome - the region of bone and periosteum that is innervated by a single spinal nerve. week 4- The compact arrangement of somite changes to become more diffuse as a result of downregulation of N cadherin (main adhesion protein holding epithelial cells together in sheet arrangement) Cells shift to surround the notochord and spinal cord. These are called the sclerotome (forming the mesenchyme) and form the vertebral column. The development is in response to bmp and Wnt signalling from the ectoderm and Shh from the notochord and the neural tube floor plate (Chan et al 2014). The sclerotome maintains it’s segmented nature as the blocks are separated by less dense areas containing intersegmental arteries. Each sclerotome consists of loosely arranged cells cranially and densely packed cells caudally. Shh regulates the sclerotome and it’s subsequent differentiation into axial skeleton. In absence of Shh the vertebral column doesn’t form. Further development occurs as the caudal portion of each sclerotome proliferates and condenses and binds to the cephalic part of the adjacent sclerotome - the precartilaginous vertebral body (resegmentation). PAX1 is expressed in 7-8 week old foetuses suggesting it has a role in segmentation between the condensed and less condensed regions.

Question 78

Resegmentation remarks theory

Answer 78

For movement to occur in the vertebral column each muscle must insert into two successive vertebrae. To achieve this the sclerotome must shift by half a segment with respect to the dermatome development. The resegmentation model was proposed by remark in 1855 to explain the realignment of the the vertebrae with respect to the muscles. Observed each sclerotome is subdivided into superior and inferior halves with different densities and separated by an intersegmental fissure. He suggested that to form a vertebra that half the sclerotomes from adjacent somite unite. Study by ward et al 2017 confirmed this theory.

Question 79

IVD formation

Answer 79

Mesenchymal cells between the cephalic and and caudal parts of the sclerotome don’t proliferate but fill the space between two precartilaginous vertebral bodies and in this way contribute to the formation of the intervertebral discs. The notochord regresses in the region of the vertebral bodies but persists and enlarges in the region of the IVD. Lineage tracing studies show the notochord cells from the nucleus pulposus which is later surrounded by the annulus fibrosus AN which combined from the IVD. The AN is formed from the sclerotome and isn’t clear how the AN cell are directed or oriented into the correct lamellar arrangement or the signal to lay down the ECM material.

Question 80

Spinal nerves c1-t2 and sclerotomes

Answer 80

The cranial part of sclerotome from c1 fuses with the caudal part of occipital 4 which then forms part of the base of the skull and explains why there are 8 cervical spinal nerves and 7 cervical vertebrae

Question 81

Chondrification of vertebrae

Answer 81

During 6th week of development chondrification centres appear in each mesenchymal vertebra At the end of the embryonic period the two centres fuse to form the cartilaginous body The centres in the vertebral arch fuse with each other and the body The spinous and transverse processes develop from extensions of the chrondrification centres in the vertebral arch.

Question 82

Ossification of the vertebra

Answer 82

Ossification begins during the embryonic period and ends about the 25th year Initially there are two primary ossification centres which soon fuse. Failure of one of these to develop leads to a wedge shaped vertebral body Two other centres are present one in each half of the vertebral arch appearing at about 8 weeks gestation. At birth each vertebra consists of three parts united by cartilage Postnatal development- two parts of the vertebral arch fuse during the first 3-5 years. Union begins in the lumbar vertebrae and progresses cranially. The joint between the arch and body disappears during 3-6 years. Until puberty the upper and lower surfaces of the body and tips of the processes remain cartilaginous when 5 secondary ossification centres appear. In the bifid cervical spines two processes appear. Final fusion occurs at about 25 years. Also until puberty the diameter and volume of the IVD increases with the vertebral column. Additional lamellae are formed but the mechanism is unknown. Chan et al 2014.

Question 83

Rib development

Answer 83

Develop from costal processes of thoracic vertebrae | Original union is replaced by synovial joints in thoracic region

Question 84

Sacrum development

Answer 84

Costal elements unite to the body and arch between ages 2-5 | The peripheral parts of bodies unite after the 20th year but the discs may persist until after middle life

Question 85

Growth and development of vertebral column

Answer 85

Growth of components determine its overall length and contribution to height of the adult. The components have different growth rates which are reflected in changes in proportion between birth and adulthood The lumbar and sacral vertebrae are relatively smaller at birth then in the adult when compared to the thoracic and cervical and thus grow the most. Thickness and height increase by growth at the annular epiphyses Vertebral column length is assessed by sitting height and in second year of life grows 5cm after which it grows 2.5cm per year until around 7 years when it grows around 1.5cm until puberty where has peak growth velocity of 4cm a year. Females on average add 6-11cm and males 7-12cm during puberty. Growth is 99% complete in females by 15 and males by 17. Adolescent growth spurt adds length due to the multiplicity of growth plates and therefore contributes a larger amount in overall height. The epiphysis close much later than those of long bones and may be seen into early 20s. The thoracic are present than other regions. IVD make up between 1/4 to 1/3 of length of the column. Their contribution is variable due to their dynamic nature as fluid changes can occur rapidly in response to postural alterations eg standing and lying down.

Question 86

Body proportions

Answer 86

Sitting height - Africans in USA and Africa have considerably longer legs than Europeans eg at sitting height 60cm euro have leg length of 45 Cm and African 51cm and Australian 61cm even longer. This is genetic origin but better environmental circumstances produce longer legs

Question 87

Developmental abnormalities of vertebrae

Answer 87

Few vertebral columns have structural symmetry and anomalies are common. In transition areas such as base of skull and between the lumbar and sacral vertebral anomalies are more common 95% of people have 7 C, 12 T, 5L, 5S fused vertebrae about 3% have additional vertebrae and 2% have less. Asymmetry of articular facets of synovial joints (articular tropism) may be cause of back pain and rotational instability which may lead to IVD problems Most common problems are failure of vertebral development, non-union of elements and segmentation failure ie several fused together Other problems - spina bifida, hemivertebrae/wedge vertebrae,

Question 88

Spina bifida

Answer 88

Most common vertebral abnormalities A non-union problem Spina bifida occulta occurs when the vertebral arch fails to either to form or fails to fuse Doesn’t occur in thoracic region and is common in S1 in 20% of people

Question 89

Hemivertebrae

Answer 89

Aka wedge vertebrae May be caused by failure of condensation at mesenchymal stage, failure of chondrification centre to develop from the mesenchyme or failure of ossification centre.

Question 90

Ageing and degeneration in vertebrae

Answer 90

During ageing trabecular and cortical bone is lost throughout the skeleton in both genders. Trabecular bone loss is much greater than cortical and as much of the vertebral bodies consists of trabecular bone there is a loss of strength with integrity of bone declining As bone mass is greater in males then females the loss is more marked in females especially after menopause when decrease in oestrogen results in less bone tissue being laid down. The loss of transverse trabeculae causes loss of height in the vertebra and may lead to micro fractures which further decrease the height. As the proportion of cortical bone increases the vertebrae becomes less resilient and more likely to fracture. Loss of trabeculae may also lead to a lack of support for the vertebral end plate and cause it to reform leading to bowing of vertebrae.

Question 91

IVD degeneration

Answer 91

IVD change with age with reduction in proteoglycan content. Result is a decrease in amount of water being bound by the nucleus and annulus. Falls from 88% to between 65-72% in nucleus between birth and 75 years. There’s a gradual increase in the relative proportion of collagen content of discs and the fibrils increase in diameter which may be due to decrease in the progenitor cell population of the disc. Result is disc becomes less resilient and more rigid. Disc height may not be reduced with age and may increase in some cases. Degeneration of discs may lead to osteophyte formation. Weakening of cartilaginous end plate can lead to dysfunction and degeneration of IVD with Schmorls nodes as most common defect which may also occur during adolescence cause is unknown.

Question 92

Schmorls node grading

Answer 92

Grade 1 age 15-40 Grade 2 age 35-75 nucleus appears fibrous and contains some brown pigment it is not degenerating. Grade 3 moderate degenerative changes with annulus bulging into nucleus. There is also end plate damage. Grade 4 severe degeneration with disruption to both end plates. The disc is reduced to both end plates. The disc is reduced in height and appears pigmented.

Question 93

Osteophytes

Answer 93

Outgrowths of healthy bone from vertebrae protecting against compressive forces They consist of compact bone and can develop at any age in response to pressure on vertebral body or disc degeneration Number of osteophytes increases with age

Question 94

Biceps brachii variations

Answer 94

Occurrence of third head - in South African populations most commonly.

Question 95

Evolution of coracobrachialis

Answer 95

Potentially the supracoracoideus and coracobrachialis muscles of dinosaur pectoral region evolve to form the two heads of corcacobrachialis in man. Coracobrachialis is pierced by the musculocutaneous nerve, single upper and several lower branches

Question 96

Supracondylar process of humerus

Answer 96

Avian spur A bony projection on the anteriomedial aspect of humerus about 5cm above the medial epicondyle. Points towards the medial epicondyle.

Question 97

Struthers ligament

Answer 97

A band of connective tissue at the medial aspect of the distal humerus Courses from the supracondylar process to the medial humeral epicondyle. Not a constant ligament, can be acquired or congenital. Clinically significant due to median nerve and brachial artery which may pass underneath its arch, can becomes compressed leading to supracondylar process syndrome. Ligament may also affect the ulnar nerve after an anterior transposition surgery commonly performed to manage patients with cubical tunnel syndrome - form of ulnar nerve entrapment. Unlikely ulnar nerve is affected without This surgery.

Question 98

Elbow joint ligaments

Answer 98

Radial collateral - lateral epicondyle to the annular ligament deep to common extensor tendon. Annular ligament of radius - anterior and posterior margins of the radial notch of the ulna on both ends forming an articular surface surrounding the head and neck of the radius (wraps round) Ulnar collateral/medial collateral - thick triangular band, two sections anterior and posterior united by thinner intermediate portion. Anterior portion runs obliquely forward attached to anterior medial epicondyle to the olecranon. Intermediate fibres attach from medial epicondyle to blend with transverse band across notch between olecranon and coronoid process. Sacciform recess of synovial membrane - not ligament but membrane of distal radioulnar joint is extremely loose and extends upwards as a sacciform recess between radius and ulna.

Question 99

Elbow collateral ligament functions

Answer 99

Posterior portion of ulnar collateral ligament is taught in maximal flexion Anterior portion contains three functional fibre bundles - taught in maximal extension, taught in intermediate positions and last is always taught and serves as a guiding bundle.

Question 100

Elbow oblique cord

Answer 100

Ligament between ulnar and radius in lower arm near elbow. Takes form of small flattened band extending down and laterally from lateral side of the ulnar tuberosity at base of coronoid process to the radius a little below the radial tuberosity. Fibres run in opposite direction to those of the interosseous membrane of the forearm.

Question 101

Pro and supination mechanisms

Answer 101

Pair of unique movements only performed by the forearm and hands Pronation - pronator teres and pronator quadratus drive this by pulling the radius and rotating it at elbow and wrist around the ulna. Distal end rotates around ulna from lateral to medial sides turning the hand 180 degrees Supination - driven by biceps brachii pulling radius distal end from medial to lateral turning the palm to face outwards.

Question 102

Cubital tunnel and ulnar nerve passage and compression

Answer 102

Formed by medial epicondyle anteriorly and medial edge of trochlea, olecranon and ulnar collateral ligament laterally and cubital gunnel retinaculum (aka arcuate ligament/Osborne band) posteriorly as the roof. Ulnar nerve passes through this and has many possible paths of compression - arcade of struthers, medial intermiscular septum, epitrochleoanconeus muscle and Osborn’s ligament all of which it passes under therefore any inflammation or tightening will compress the nerve resulting in weaknesses such as Wartenburgs syndrome where the little finger is involuntarily abducted by extensor digiti minimi.

Question 103

Trapezius

Answer 103

Broad flat and triangular Attaches from skull, nuchal ligament and spinous processes of c7-t12 Inserts to the clavicle, acromion and scapula spine Innervation - motor from accessory nerve and proprioceptor fibres from c3 and 4 spinal nerves Upper fibres elevate and rotate scapula during arm abduction Middle fibres retract scapula Lower fibres pull scapula inferiorly

Question 104

Latissimus dorsi

Answer 104

Origin- lower back spinous process of t6-12, iliac crest, thoracolumbar fascia and inferior three ribs Fibres converge into tendon inserting into intertubercular sulcus of humerus Innervation from thoracodorsal nerve Extends, adducts and medically rotates upper limb

Question 105

Levator scapulae

Answer 105

Origin - transverse processes of c1-4 Inserts to medial boarder of scapula Innervation from dorsal scapula nerve Elevates scapula

Question 106

Rhomboids

Answer 106

``` Major - Origin from spinous processes of t2-5 Inserts on medial boarder of scapula between spine of scapula and inferior angle innervation dorsal scapula nerve Retracts and rotates scapula Minor - Origin spinous processes of c7-t1 Inserts on medial boarder of scapula at level of scapula spine Innervation dorsal scapula nerve Retracts and rotates scapula ```

Question 107

Extrinsic superficial muscles of the back

Answer 107

Latissimus dorsi, trapezius, rhomboids and levator scapulae | Act to move the shoulder

Question 108

Extrinsic intermediate muscles of the back

Answer 108

``` Serratus posterior (superior and inferior) muscles Act to move thoracic cage ```

Question 109

Serratus posterior muscles

Answer 109

Deep to the rhomboids Serratus posterior is two thin, intermediate back muscles which lie above the intrinsic back musculature. They are: The serratus posterior superior muscle The serratus posterior inferior muscle Superior - spinous processes and supraspinous ligaments of c7-t2 Insertion into posterior aspect of ribs 2-5. Assists forced inspiration elevating ribs Supplied by anterior primary rami (t2-5) intercostal nerves. Inferior - spinous processes and supraspinous ligaments of t11-L2 Inserts in posterior aspect of ribs 9-12 Assists forced expiration depressing spine Supplied by primary rami t9-12 intercostal nerves

Question 110

Intrinsic superficial muscles of back

Answer 110

Known as spinotransversales Muscles - splenius capitis and splenius cervicis Act to stabilise or move the vertebral column

Question 111

Splenius capitis muscles

Answer 111

Origin from lower aspect of ligamentum nuchae and spinous processes of c7-t3/4 Insert to mastoid process and occipital bone of skull. Innervated by posterior rami of spinal nerves c3 and 4 Function to rotates head to the same side

Question 112

Splenius cervicis muscle

Answer 112

Origin from spinous processes of t3-6 Insert into transverse processes of c1-3/4 Innervated by posterior rami of lower cervical spinal nerves Function to rotate head to same side

Question 113

Intrinsic intermediate muscles of back

Answer 113

Iliocostalis, longissimus and spinalis known as the erector spinae. All have a common tendinous origin arising from the lumbar and lower thoracic vertebrae, sacrum, posterior aspect of iliac crest and sacroiliac and supraspinous ligaments. Iliocostalis - inserts into costal angle of the ribs and the cervical transverse processes. Innervated by posterior rami of spinal nerves, is the most lateral of the muscles and acts to laterally flex the vertebral column. Acts bilaterally to extend the vertebral column and head. Longissimus - between the other two muscles. Inserts into the lower ribs and transverse processes of c2-t12 and mastoid processes of the skull. Innervated by posterior rami of spinal nerves and acts unilaterally to laterally flex vertebral column and acts bilaterally to extend the vertebral column and head. Spinalis - most medial of the muscle inserts to spinous processes of c2, t1-8 and occipital bone of skull. Innervated by posterior rami of spinal nerves. Acts unilaterally to laterally flex the vertebral column and acts bilaterally to extend the vertebral column and head.

Question 114

Deep instrinsic muscles of back

Answer 114

Known as transversospinales Short muscles associated with transverse and spinous processes of the vertebral column Three major muscles - semispinalis, multifidus and rotatores.

Question 115

Semispinalis

Answer 115

Most superficial of the deep intrinsic muscles of the back. Originated from transverse processes c4-t10 inserting to c2-t4 and occipital bone Innervation from posterior rami of spinal nerves acts to extend and contralaterally rotate head and vertebral column

Question 116

Multifidus

Answer 116

Located underneath semispinalis and is best developed in the lumbar area Has broad origin from sacrum, posterior iliac spine, common tendinous origin of erector spinae, mamillary processes of t1-3 and articular processes of c4-7. Insert to spinous processes of vertebrae Innervated by posterior rami of spinal nerves acts to stabilise the vertebral column

Question 117

Rotatores muscle

Answer 117

Most prominent in thoracic region Origin from vertebral transverse processes Inserts into lamina and spinous processes of immediately superior vertebrae Posterior rami of spinal nerves innervate Acts to stabilise the vertebral column and has proprioceptive function.

Question 118

Minor deep intrinsic muscles of back

Answer 118

Interspinales - spans between adjacent spinous processes and acts to stabilise vertebral column Intertransversari - spans between adjacent transverse processes acts to stabilise vertebral column Levatores Costarum - origin from c7-t11 insertion to rib immediately below acts to elevate ribs.

Question 119

Scoliosis

Answer 119

Abnormal lateral curvature of the spine Most common in thoracic spine region Most often starts in children ages 10-15 Infantile idiopathic scoliosis - develops at ages less than 3 Juvenile idiopathic - between 3-10 years Adolescent idiopathic - between 10-18 years More than 80% of people with scoliosis is idiopathic and majority of those are adolescent girls. Doesn’t normally improve without treatment but treatment isn’t always needed if mild Can have back pain and look lopsided - shoulder not aligned etc Can cause severe breathing problems Can be treated with back brace sometimes surgery needed and treatment to manage the pain Decreases chest wall compliance directly and lung compliance indirectly due to progressive atelectasis (Lung collapse) and air trapping significantly increasing the work of breathing. Any associated respiratory muscle weakness may lead to respiratory failure if severe enough The cobb angle is a measurement of the degree of scoliosis. An X ray of the patient is taken, and an angle between the top and bottom vertebrae involved in the condition (not the straight ones) is drawn. Perpendicular lines are then drawn from each line and the intersection of these is the Cobb angle. (Top bit of intersection) Must be angle of 10degrees or more for scoliosis.

Question 120

Kyphosis

Answer 120

Excessive outward curvature of spine causing back hunching A curve of more than 45 degrees (nhs) Can cause back pain, stiffness, spine tenderness and tiredness. Can also be asymptommatic. Particularly problematic in adults due to having to compensate for abnormality. May lead to difficulty breathing and eating if severe enough Caused by poor posture, abnormally shaped vertebrae (Scheuermanns kyphosis), congenital kyphosis from abnormal development in womb ie vertebrae fusing together, or age can naturally increase curvature. Can also develop as result of spinal injury. Children can be treated with bracing etc or surgery rarely.

Question 121

Lordosis

Answer 121

Excessive inward curvature of the spine Can be caused by spondylolisthesis (spinal condition where lower vertebrae slip forward onto bone below), osteoporosis, obesity etc. Types : lordosis of lumbar spine is most common. Cervical lordosis the neck is a very wide C or runs outward (reverse cervical lordosis). Only requires treatment if severe Juvenile lordosis often occurs without cause when muscles in children’s hips are weak or tightened. Typically corrects itself with age

Question 122

Vertebral body weight bearing

Answer 122

Anterior body withstands 75% weight and posterior 25% of longitudinal load They’re shall of cortical bone surrounding trabecular framework Solid (cortical) bone suitable for maintaining static load as dynamic load would disrupt their crystalline structure and fracture along cleavage planes. Anterior triangle made up of mainly trabeculae and explains why you get wedge shaped fractures. 600kg would crush anterior part of healthy vertebrae while 800kg would crush the whole body. Ability to withstand forces and load is dependent on bone mass with peaks in mid thirties and then slowly declines In women this decline accelerates at a higher rate after menopause for about 10 years after Trabecular bone mass declines more rapidly than cortical bone and alters loading properties of vertebral body

Question 123

Trabecular pattern pedicle

Answer 123

Pedicles are the only connection between posterior elements and body and all forces sustained by posterior elements are ultimately channelled towards the pedicles which transmit them to body Designed to sustain force and trabecular pattern makes them very strong

Question 124

Lamina force transmittence

Answer 124

Contain articular facets which upper cervical region support forces acting between vertebral column and the head From the third cervical vertebral forces are transmitted from lamina to body through the pedicles and therefore must be strong to withstand bending forces

Question 125

Articular process and force

Answer 125

Paired superior and inferior processes project from laminae- faces of which form small synovial joints These determine range of movements possible between vertebrae as well as shape of articulation, position of ligaments and muscles as it’s a synovial joint. Major difference between vertebral column and other synovial joints is most forces generated go through body of vertebrae and not synovial joint itself with the exception of first two joints at base of skull. Second difference is position of ligaments which aren’t all intimate with vertebral articular joints as they are in other parts of the body.

Question 126

Lumbar region and force

Answer 126

Synovial joints designed to block axial rotation protecting the intervertebral discs from excessive tension Anterior sliding also prevented as orientation of joints acts as a block

Question 127

Lumbrosacral joint

Answer 127

In upright position sacrum is inclined 50 degrees forward Lumbar vertebra prevented from slipping forward and downward on the sacrum by: IVD wedged at 16 degree lessens angle on superior surface of sacrum Superior articular facet of sacrum face posteriorly at an angle between 45-90 degrees Hooking inferior articular facet of L5 into sacrum preventing it from sliding forward and in addition the transverse process of L5 are secured by iliolumbar ligaments

Question 128

Sacroiliac joint

Answer 128

Synovial but not designed for large range of movement limited to about 2 degrees No muscles to provide movement Acts as stress relieving joint in pelvic girdle During gait pelvis is subject to twisting forces therefore if this joint was solid it would crack Surrounded by strong ligaments that help absorb forces applied during gait

Question 129

Secondary cartilaginous joints of vertebral column

Answer 129

Synovial joints would be unable to function without some movement of vertebral bodies To sustain the forces and prevent sliding a strong layer of deformable material is in between each vertebra Intervertebral discs Has three components - nucleus pulposus, annulus fibrosus and end plates

Question 130

Nucleus pulposus of IVD anatomy

Answer 130

In young healthy adults is semi fluid mass 70-90% water with few cartilage cells 1-5% total volume Irregularly arranged collagen fibres mostly type II but up to 10 different types present dispersed in ground substance containing proteoglycans Aggrecan is most abundant proteoglycan and may attach to hyaluronic acid to form even larger molecule No blood vessels or nerves May be deformed but volume can’t be compressed When force is applied it reduces height and expands radically putting pressure on annulus which stretches lamellae outward resisted by collagen. Nucleus also exerts pressure on end plates which may bulge Disc has resilience as once pressure is removed is restored to original position

Question 131

Annulus fibrosus IVD anatomy

Answer 131

In the lumbar region consists of highly ordered collagen type I fibres mostly arranged in concentric rings anteriorly thicker 40% rings incomplete Proteoglycans also present and glycoproteins Is turgid and relatively stiff and when healthy will resist buckling and bear weight After prolonged weight bearing will begin to deform - collagen lamellae will buckle and fluid will be squeezed out Negative charge on GAGS prevents complete collapse of integrity of disc Loss of proteoglycans is first indication of disc degeneration Alterations In direction of fibres in lamellae are integral to capacity of disc to resist twisting

Question 132

Differences in IVD composition in vertebrae

Answer 132

Most studies look into lumbar region. Some evidence indicate differences in cervical discs with nucleus pulposus forming only 25% in cervical but 50% in lumbar. Also differences I arrangement of annulus. Few studies on thoracic region suggest its similar to cervical.

Question 133

Vertebral end plates

Answer 133

0.6-1 mm thick covering area of pulposus but not all of annulus. (Peripheral of annulus inserted into bone) Collagen fibres in hyaline cartilage arranged horizontally at centre to withstand pressure form nucleus during axial compression Vertebral end plate is weak link in compression as needs to be thin to pass nutrients to discs but pressure from nucleus can cause it to bulge into vertebra Cranial end plate is weaker than caudial

Question 134

IVD function

Answer 134

Fluid loss and gain is exponential If forced added and removed in quick succession fluid gain may not return to original state If force is maintained for long period of time disc might not recover to initially thickness Pressure - muscle tension increases compressive force on disc. Higher forces generated during movement To support joint and prevent unwanted movements several ligaments surround vertebral column Anterior longitudinal ligament - slack in forward flexion stretch in extension. Posterior longitudinal ligament - reverse.

Question 135

Range of movement in vertebral column

Answer 135

Range of movement between two adjacent V is limited due to limited range of IVD deformation and shape of articulation, associated ligaments etc. While individual movements are small, summation of all these produce wide range of movement During movement is subject to tension, Compression, bending, torsion and shearing forces Flexion and extension of atlanto occipital joint averages 15 degrees but only small degree of lateral flexion always accompanied by rotation. Lateral flexion usually coupled with contralateral rotation in upper lumbar region but with ipsilateral rotation at L5/S1 Many movements of vertebral column are coupled but there’s a high degree of variability between individuals.

Question 136

Loading forces acting on vertebral column

Answer 136

Axial compression occurs due to force of gravity and action of ligaments and muscles When subjected to constant load disk will exhibit creep which causes fluid to be expressed from the disc. Removal of load allows disc to return to normal condition Annulus and trabecular bone can undergo greater amounts of deformation before failure than end plate or cortical bone Can

Question 137

Vertebral column muscles

Answer 137

Divided into trunk and neck muscles Posterior muscles further divide into extrinsic, superficial and deep and intrinsic superficial and deep. Also anterior muscles which lie in front of vertebral column and in front of viscera in the neck, thorax and abdomen. Trunk muscles - consist of posterior vertebral muscles divided into extrinsic (attaches to upper limb), superficial intrinsic and deep intrinsic. In front of vertebrae are psoas and quadratus lumborum muscles and also important group forming anterior abdominal wall-transversus abdominis, internal and external obliques. Posterior muscles - tightness of erector spinae often present in back pain. In normal standing there’s little activity in muscle. Constant activity to counteract forward sway is increased when head or upper limbs move forward. Contraction of erector spinae increases intracranial pressure. Transversospinalis muscles act as postural muscles stabilising vertebrae and controlling movement. Quadratus lumborum acts as respiration accessory fixing 12th rib and stabilising origin of diaphragm. Flexes trunk ipsilaterally and aided by oblique muscles. Psoas major when femur foxed and hip stabilises contracts leading to ipsilateral lateral flexion and contralateral rotation. Creates compressive force on IVD and increases intradiscal pressure. Flexes VC relative to pelvis accentuating lumbar lordosis. Thoracolumbar fascia also surround muscles

Question 138

Fascia of vertebral column - thoracolumbar fascia

Answer 138

Thoracolumbar, fascia lata and abdominal fascial systems play important role in stability and mobility Thoracolumbar covers back muscles over sacral region extending through thoracic region to nuchal line. Complex fascia has several layer. Many fibres of superficial layer derived from aponeurosis of lat dorsi and blend with fascia of gluteus max. Also continuous with contralateral lat dorsi. Muscles are mechanically linked and play role in increasing fascia tension in turn stabilising lumbosacral and sacroiliac regions. Deep fibres attach to interspinius ligaments, posterior iliac spine, crest and sacroiliac ligament. Laterally two layers blend together and are directly linked to internal oblique and transversus abdominis muscles. Functions- stabilise pelvis. Muscles in contact with (transversus abdominis, internal oblique, glut max, lat dorsi) have a pulling effect on fascia. Muscles encased by it (erector spinae, multifidus) have pushing effect. Movement of limbs and back also increase tension May also aid alignment of vertebral column by reducing shear forces. May prevent buckling of ligamentum flavum.

Question 139

Abdominal muscles and vertebrae movements

Answer 139

Bilateral contraction increases intra abdominal pressure but doesn’t result in trunk flexion. Aided by contraction of internal oblique Play important part in expulsion efforts increasing pressure on bladder, rectum, stomach and in childbirth. Intra abdominal pressure also increased during lifting accompanied by closing glottis and contraction of pelvic floor muscles. Axial compression of discs reduced and therefore useful for protecting vertebral column in short term when lifting heavy load

Question 140

Spinal flexion

Answer 140

Increased activity in erector spinae muscles Gravity Produces movement but it’s rate is controlled by erector spinae and multifidus contracting eccentrically. At 90degree flexion erector spinae activity ceases Tension in facet joints and posterior ligaments braces the spine Activity in anterior and lateral muscles occurs only when working against gravity

Question 141

Spinal rotation

Answer 141

Oblique muscles main rotators External oblique from one side works synergistically with opposite side Fibres of muscle form a girdle around abdomen Slant of muscle determines hollow of waist Higher the tone of muscle the greater the hollow Mathematical explanation is a hyperbolic curve, curve consists of series of straight lines

Question 142

Palpating joints of elbow

Answer 142

Palpated inside triangle formed by bony prominences of lateral epicondyle, radial head and the olecranon. This palpitation reveals even minor effusions or mild synovitis. Puncture for joint aspiration performed in this triangle Similarly an arthroscopy portal may be placed there (posterolateral portal) Anatomical landmarks - lateral aspect of elbow, radial head palpated with thumb while other hand pro and supinates patients forearm

Question 143

Elbow injuries/problems

Answer 143

Bursitis - bursa inflammation Medial joint pain - Valgus injuries often from throwing action Epicondylitis - golfers elbow (medial) - common in men 20-50 years, pain in medial elbow may radiate to inner forearm. Worsens when making goats or shaking hands. Treated by analgesia NSAIDS, steroid injection, physio. tennis elbow (lateral) - degeneration of tendon fibres over lateral epicondyle involved in wrist extension. Severe burning pain on outer elbow. Worsens when gripping or lifting and with direct pressure on lateral epicondyle. May radiate down forearm. Fractures and dislocations - ulnar, radial And humeral. Fall backwards onto extended arm Pulled elbow - wrestlers and children most commonly. Nerve and vascular entrapments - ulnar, median, radial nerves and brachial artery

Question 144

Elbow dislocations

Answer 144

Described according to direction of displacement of ulna relative to humerus posterior has many variations - Posterolateral, posteromedial, lateral and medial. Anterior is very rare Usually stable once reduced if bony stability is good. Complex injuries - radial head fractures cause instability, MCL always damaged to varying degrees. May have fracture of medial epicondyle. Coronoid fractures: fall into flexed elbow, due to avulsion by brachialis when elbow is hyperextended. Terrible triad - radial head, coronoid and MCL often damaged together. Median and ulnar nerve injuries in 20% cases. In simple cases both collateral ligaments usually torn but MCL can survive. Variable amount of muscle origin lost. Greater instability with more muscle injury.

Question 145

Pulled elbow

Answer 145

``` Usually 18 months to 4 years most common Partial dislocation of elbow History of pulling arm, won’t use arm Not very distressed Any movement causes a clicking noise ```

Question 146

Elbow fractures

Answer 146

Humeral - supracondylar, hyperextension of arm on outstretched hand/direct blow to humerus. Or flexion type from direct force to tip of elbow. Ulnar - coronoid, olecranon: impact or hyperextension Radial - axial loading of radius from fall or dislocation. Pain on outside elbow, swelling, unable to fully flex or extend, pain with pro and supination. Intercondylar/condylar/epicondylar type - medial epicondyle commonly avulsed during elbow dislocation. Nearly always associated with another dislocation. Capitular fractures - transmission of force through radial head when landing on hand with elbow flexed or directly onto fully flexed elbow. Olecranon and coronoid fractures - direct impact on posterior surface of elbow or indirect falls into hand. Often associated with ulnar nerve injury (10%) Radial head fractures - fall onto outstretched hand

Question 147

Supracondylar fractures of elbow complications

Answer 147

Vascular - brachial artery damaged, Volkmanns ischaemic contracture (permanent flexion of hand at wrist - claw hand from extension of MCP and flexion of IPJ), median nerve palsy. Treatment - manipulation if displaced, arterial obstruction fixed Long term arm plaster

Question 148

Complications of elbow injuries

Answer 148

Neurovascular injury - ulnar, median, radial nerves and brachial artery (radial least common) Osteoarthritis - osteophytes formation. Primary commonly seen in males 50-60 years repetitive elbow use. Secondary most commonly from post trauma. Catching or locking loose bodies in 20% cases. Terminal impingement pain from olecranon osteophytes possible. Loss of motion usually extension. Ulnar nerve irritation common. Rheumatoid arthritis Synostosis union or fusion of bones by growth of bony substance - congenital or acquired/post traumatic

Question 149

Kidneys function

Answer 149

Maintaining overall fluid balance Regulating and filtering minerals from blood Filtering waste materials from food, medications and toxic substances Creating hormones that help produce red blood cells, promote bone health and regulate blood pressure

Question 150

Describe the kidneys

Answer 150

Bean shaped organs retroperitoneal at level t12-l3 Left higher than right due to liver on right hand side Renal capsule surrounded by peri-renal fat, then renal fascia and pararenal fat. Supplied by renal arteries from aorta at L1 just underneath superior mesenteric artery branching. Renal arteries become interlobar either side of pyramids, then interlobular then entering the cortex become afferent arterioles forming capillary nertwork ending in efferent arterioles forming peritubular network around nephrons then vasorecta supplying inner 1/3 of cortex and the medulla. Renal vein on the left is longer due to crossing the aorta and artery on the right is longer due to crossing the IVC. Lymph drains into paraortic lymph nodes. Drained by renal veins (lies anterior to artery in hilum). Cortex contains vessels and nephrons - take in and filter blood for waste metabolites. Each kidney has roughly 1 million nephrons. Blood enters renal corpuscle (aka malpighigan body) containing the glomerulus and bowmans capsule. Then passes through into renal tubules - PCT, loop of henle and DCT absorbing water, sodium and glucose (PCT), K, Cl and Na (LoH), Na, K and acid (DCT) back into blood. Passes into collecting tubules in the medulla (LoH also dips into medulla) drains into renal pyramids containing strings of nephrons tubules finally moves into renal pelvis by minor and major calyces. Small cup shaped spaces that collect fluid before it moves to the bladder. Also where extra fluid becomes urine. Exits via the ureter through the hilum of the kidney into the bladder.

Question 151

Ureter narrowings

Answer 151

Pelvi-ureteric junction - renal pelvis and ureter Pelvic brim where ureter passes over iliac vessels Vesicoureteric junction where ureter enters bladder These can be involved in kidney stones pain as they’re the narrowest points and are where stones will most likely get stuck. Causes sharp cramp in back, side or lower abdomen.

Question 152

Ureter blood supply and innervation

Answer 152

Arterial blood supply varies along course Upper part closest to kidneys - renal arteries Middle part from common iliac arteries direct branches from abdominal aorta and gonadal arteries (testicular/ovarian arteries) Lower part closest to bladder - internal iliac arteries as well as superior vesicle artery, uterine artery in women, middle rectal artery, vaginal artery in women and inferior vesicle artery in men only. Nerve supply ureteric plexus. Primary sensation from T12-L2.

Question 153

Can you cut the left renal vein without serious consequence

Answer 153

Yes as the left renal vein crosses the aorta so it is often necessary in surgery to sacrifice it luckily there are collateral drainage vessels from inferior adrenal veins that compensate for this.

Question 154

Retroperitoneal organs

Answer 154

``` SAD PUCKER Suprarenal glands Aorta/IVC Duodenum after 1st section. Pancreas Ureters Colon (ascending and descending) Kidneys Oesophagus ```

Question 155

Kidney topographical anatomy

Answer 155

Anterior (left) - spleen, stomach, splenic flexure, pancreas, jejunum, adrenal glands Posterior (left and right)- psoas, quadratus lumborum, 11/12 ribs Anterior (right)- liver, hepatic flexure, duodenum, adrenal glands

Question 156

Mechanical damage to lumbar spine

Answer 156

Impairment of structure unable to withstand forces generated by normal activities For fatigue failure to occur the microscopic damage must accumulate faster than the adaptive remodelling response can cope with Repetitive mechanical loading and micro damage resulting from it can initiate adaptive remodelling response so that the spine can become stronger and more able to withstand load Bone remodels in response to increase load as does muscle Both will also adapt to a decrease in load. The metabolism and age of tissue dictate the rate of remodelling.

Question 157

Compressive Load on vertebral column

Answer 157

Compressive load is resisted mostly by anterior column and IVD 75-85% while facets joints and laminae give rise to remainder of resistance. Narrowing of IVD leads to increase in facet load. If narrowing is severe up to 70% load may be transmitted through facet joints. In lumbar spine compressive strength of vertebrae ranges between 2-14kN depending on age, sex and body mass. Trabecular pattern of bone reenforces body but makes anterior portion more vulnerable to compression. Compression of vertebra while In full flexion may effect either disc or vertebra.

Question 158

Compression and fracture of vertebrae

Answer 158

In older subjects with osteoporosis anterior wedge fractures are more common. Fractures of body of vertebra are also more common following degeneration of IVD as it impairs ability of the disc to reduce stress on both body and posterior arch Compression fractures most common type and occurs most frequently in thoracic region. Occurs during loading of spine combined with flexion or lateral flexion and in absence of trauma but spine is either overloaded or weakened by conditions such as osteoporosis. Fractures thought to occur more in thoracic region as it’s stiffer than more mobile lumbar region. Types of vertebral compression failure - stellate, step, intrusion, transverse, edge, Y, depression. Relationship between vertebral strength and structure is complex involving contributions from end plate, cortical shell, trabeculae and IVD. Strength of bone significantly more sensitive to loss of trabeculae compared with similar overall reduction in bone mass

Question 159

Facet joint damage of vertebrae

Answer 159

In extension the posterior arch resists 60-70% applied force and increases further if there’s also a compressive force The IVD resists remainder of load Most likely area of damage in extension is to facet joint. Rapid extension movements with occur in gymnastics, athletics, tennis and cricket may fracture area between joints (pars interarticilaris) while failure might also occur with repeated loading in such manual activities leading to spondylolysis

Question 160

Causes of disc failure

Answer 160

Vertebral end plate failure Compression loading damages end plate before IVD End plate in young adults is flat but develops concavity with increasing age and may indicate repeated minor injuries to end plate or trabeculae supporting them. Mechanism of failure initiated by nucleus pulposus causing end plate to bulge into vertebrae End plate lesions very common in lumbar disc herniation and is likely that the end plate, rather than annulus is primary site of pathology Bending stretched and thins annulus reducing strength. If compression force simultaneously applied pressure raised in nucleus and can herniate through annulus or annulus may collapse outwards. Flexion produces High stress both axial and circumferential leading to most unsafe condition which may result in annular failure Might also be caused by repetitive loading combining compression, flexion and lateral flexion. Annulus becomes deformed eventually rupture of lamellae can occur at both corners. Usually only small quantity of nucleus escapes but once released from confines of disc it may swell. Over time proteoglycans peak out and tissue shrinks. Asymmetric facet joints may contribute to disc degeneration by causing disc to flex on oblique axis rather than symmetrical axis. Lateral bending stretches peripheral annulus more than forward bending.

Question 161

Osteophytes

Answer 161

Damage to structures which limit movement of vertebral column can lead to instability of damaged segment Fluid may be lost from disc due to sustained loading or disc degeneration leading to slackness of ligaments and annulus and may lead to joint laxity. Development of osteophytes which occurs when discs degenerates, restores stability but usually accompanied by reduction in ROM

Question 162

Consequence of disc failure

Answer 162

Load sharing lumbar spine affected by disc degeneration. Normal disc function the neural arch resists only 8% of applied compressive force with remainder almost equally distributed over the vertebral body However disc degeneration causes increase in neural arch resistance to 40% of applied compressive force

Question 163

Spondylolysis and spondylolisthesis

Answer 163

Idiopathic defect which develops on one or both sides of neural arch in 85% cases on L5 and most of remainder on L4 and occurs in about 10% of adults May be results of fragile fracture often asymptomatic but can cause back pain If from fracture of pars interarticilaris may result in forward movement of vertebrae and form spondylolisthesis - Present in 2% adults Means vertebral displacement occurs when lamina fails. Nearly always occurs between L4/5 or sacrum. Usually painless in children and possibly associated with scoliosis. In adults may present and intermittent backache exaggerated by exercise. Has appearance of Scotty dog with collar.

Question 164

Joints of wrist

Answer 164

Radiocarpal - true joint/wrist joint proper Ulnocarpal - between articular disc and carpal bones Midcarpal (most flexion of wrist occurs here) and intercarpal joints Carpometacarpal joints Distal radioulnar joint.

Question 165

Bones of the hand

Answer 165

Carpal bones - some lovers try positions that they can’t handle Radial to ulna proximal row - scaphoid, lunate, triquetrum, pisiform (Not real carpal bone!!) Distal row - trapezium (under the thumb), trapezoid, capitate, hamate. metacarpals - 5 each related to a digit Phalanges most distal bones - finger bones each has three except for thumb which has two.

Question 166

The TFCC

Answer 166

Triangular fibrocartilanginous complex - cartilage structure located on small finger side of wrist that cushions and supports small carpel bones of wrist. Keeps ulna and radius stable when hand grasps or forearm rotates Injury or tearing can cause chronic wrist pain

Question 167

Carpal ligaments

Answer 167

Many ligaments to support and protect movements in the wrist and carpal bones Extrinsic - volar/Palmer radiocarpal ligaments: radioscaphocapitate, long radiolunate, radioscapholunate, short radiolunate. Volar ulnocarpal ligaments: ulnotriquetral, ulnolunate, ulnocapitate Dorsal ligaments - radiotriquetral, dorsal intercarpal, radiolunate, radioscaphoid Intrinsic dorsal ligaments - scapholunate, lunotriquetral, trapeziotrapezoid, capitohamate Intrinsic Palmer ligaments - scaphotrapeziotrapezoid, scaphocapitate, triquetralcapitate, triquetralhamate Palmer ligaments are thought to be much stronger and more important in movement and stability than dorsal These ligaments will twist as bones rotate and causing forearm limbs to stretch in rotation etc.

Question 168

Development of hand and abnormalities

Answer 168

Growth plates appear at different points in different bones 2- ossification centre in hamate, 4 lunate, 5 scaphoid, 6 trapezoid, 7 trapezium and pisiform not until age 12 therefore evidence it’s not a true carpal bone. Growth plates in metacarpals seen travel distally while in the thumb it travels proximally thought that this is because it’s actually a third phalanx not a metacarpal - last metacarpal in evolution instead of loosing the third phalanx? Unsure still debated. Possibly just difference in timing of fusion in thumb to other digits. Evidence from bone disorders such as cleidocranial dysostosis - bone disorder with absence of clavicles and skull and hand malformations - often see two growth plates at distal and proximal end of phalanxes suggesting just has different fusion times in normal growth. Triphalangeal thumb condition suggests it is a metacarpal bone as rare condition causes no thumb growth only fifth finger to grow with extra phalanx present. Brachymetacarpalis - condition of shortened metacarpal bones makes gripping difficult etc. Gender differences - usually females have equal sized ring and index fingers or longer index than ring. Males tend to have larger ring finger and lower 2D:4D ratio. Indicates higher testosterone levels while higher ratio indicates lower testosterone levels.

Question 169

2D:4D Hand ratio

Answer 169

Gender differences in hands- usually females have equal sized ring and index fingers or longer index than ring. Males tend to have larger ring finger and lower 2D:4D ratio. Indicates higher testosterone levels while higher ratio indicates lower testosterone levels. Prostate cancer - men with longer index fingers than ring fingers are significantly less likely to get prostrate cancer as have less testosterone? Linked to testosterone levels?

Question 170

Surface anatomy of hand

Answer 170

Distal transverse, proximal transverse, radial longitudinal crease, middle Palmer crease, thenar crease, distal, middle and proximal creases of wrist. Middle crease of wrist is where wrist joint lies. Also have proximal, middle and distal creases of phalanxes. Creases are slightly proximal to the actual joints.

Question 171

Joints of hand and type of joint

Answer 171

Distal inerphalangeal - all hinge joints Proximal IP joints - all hinge MCP - all biaxial condyloid aside from first which behaves like a hinge CMC - all ellipsoid aside from first which is a saddle joint

Question 172

Trapezo-metacarpal joint ligaments

Answer 172

Needs specialised ligaments due to thumb angle making it likely to pull back in wrong direction often caused from ski poles etc. Ulnar collateral ligaments help stabilise and resist pressure as well as anterior oblique ligaments.

Question 173

Describe the adrenal/suprarenal glands

Answer 173

Retroperitoneal organs sat superior to kidneys. Encased in parietal peritoneum. Left adrenal gland is semilunar shaped while the right is pyramidal shaped. Perinephric (renal) fascia encloses adrenal glands and kidneys attaching them to the crura of the diaphragm. Separated from kidneys by perirenal fat. Right adrenal gland is anterior to the right crus of diaphragm and posterior to the IVC and right lobe of the liver. The left is anterior to the left crust of diaphragm and posterior to the stomach, pancreas and spleen. They consist of outer connective tissue capsule, cortex and medulla. Veins and lymphatics leave via their hilum but arteries and nerves enter glands at numerous sites. Cortex derived from mesoderm and medullary from ectodermal neural crest cells. Cortex is yellowish in colour and is functionally divided into three from outer to inner - zona glomerulosa secretes mineralocorticoids such as aldosterone, zona fasciculata secretes corticosteroids like cortisol and small amount of androgens, zona reticularis secretes androgens like DHES and small amount of corticosteroids. The medulla lies in centre and is dark brown. Contains chromaffin cells which secrete catecholamines in response to stress. Also secrete enkephalins which are involved in pain control. Supplied by superior, middle and inferior adrenal arteries. Superior from inferior phrenic artery, middle from abdominal aorta and inferior from renal arteries. Innervated by coeliac plexus and abdominal splanchnic nerves. Sympathetic innervation mainly from T10-L1 spinal cord. Lymph drainage into lumbar lymph nodes by adrenal lymph vessels originating from two plexuses, one deep to the capsule and one in the medulla.

Question 174

Main functions of urinary system

Answer 174

Removal of metabolic waste like uric acid, urea and creatinine Maintain electrolyte, water and pH balance Regulation of BP, blood volume and erythropoiesis and vitamin D production

Question 175

Development of kidneys

Answer 175

Closely related to reproductive system particularly in early stages but develops slightly ahead of reproductive system. Consists of kidneys, ureters, bladder and urethra. The intermediate mesoderm called the urogenital ridge gives rise to all structures. Develops from three overlapping sequential systems- pronephros, mesonephros and metanephros. Pronephros - development begins at cervical region of embryo in fourth week of development. Segmented divisions of intermediate mesoderm form tubules called nephrotomes. 6-10 pairs of nephrotomes are formed these joint to form the pronephric duct which extends from the cervical region to the cloaca of the embryo. Non functional and regresses completely by the end of week 4. Mesonephros - develops caudally (inferiorly) to pronephros. Presence of pronephric duct induced nearby intermediate mesoderm in thoracolumbar region to form mesonephric tubules which receive capillaries from dorsal aorta allowing filtration of blood which drains into mesonephric duct (continuation of pronephric duct). Act as primitive excretory system in embryo. Most tubules regress by 2 months. Also sprouts the ureteric bud caudally which induces the definitive kidney. Metanephros - forms definitive kidney. appears in week 5 and is functional in 12th week. Ureteric bud forms mesonephric duct and contacts caudal region of intermediate mesoderm (metanephric blastema) to form metanephric system. Has two parts - collecting system derived from ureteric bud creating the ureter, renal pelvis, major and minor calyces and collecting tubules terminating at DCT. If splits too early may result in two ureters or renal pelvises. And the excretory system derived from metanephric blastema, forming the nephrons (bowmans capsule, glomerulus, PCT, loop of henle and DCT). Initially develops in the pelvic region before ascending to abdomen. In pelvis receives blood supply from pelvic branch of aorta and as it ascends new arteries supply. Pelvic vessels regress but can persist as accessory arteries.

Question 176

Development of bladder and urethra

Answer 176

Cloaca forms bladder and urethra. In weeks 4-7 cloaca is divided into two by uro-rectal septum. Urogenital sinus (anterior) forms bladder and urethra as well as some reproductive tract in females and prostatic, membranous and spongy urethra in males. Anal canal posteriorly initially drained by allantois but this is removed in foetal development and becomes fibrous cord (urachus). Remnant of this found in adults - median umbilical ligament connecting bladder to umbilicus. As bladder develops it absorbs caudal parts of mesonephric ducts (wolffian ducts) becoming trigone of bladder. Ureters enter at base of trigone.

Question 177

Horseshoe kidney

Answer 177

Renal fusion is a congenital disorder affects 1 in 600 people, more commonly men. 0.25% of the population. Kidneys fuse to form horseshoe shape during development and are blocked by the inferior mesenteric artery at L3 from rising higher. Fused section called the isthmus can be metanephric tissue or just thick band of connective tissue. Can be connected at the midline or in 70% cases is shifted to the left. Isthmus is directly below the IMA in 40% patients but in 20% kidneys just don’t rise higher than the pelvis naturally ectopic. Rotation causes anterior facing hilums causing drainage problems increasing infection risk and stone risk. Often have around 40 x more arterial supply than expected but have poor collateral supply - supply only specific bits of kidney no anastomoses. Diagnosed with CT, MRI, ultrasound etc. Causes altered position, rotation and blood supply of kidneys. At increased risk for kidney stones, miscarriage, pain, renal cell carcinoma and hydronephrosis. Mostly asymptomatic

Question 178

Panda opposition of hand

Answer 178

Only other animal to be able to do something similar to thumb opposition in humans Uses fat filled pouches on palm of hand opposes them to fingers in order to grip objects like bamboo.

Question 179

Types of grip

Answer 179

Static - digital (use fingers), precision grips Power, Palmer grips and hook grips Dynamic grips - moving objects in our hands eg play instruments

Question 180

Define flexor retinaculum

Answer 180

Transverse carpal or anterior annular ligament is a fibrous band on Palmer side of hand near the wrist Arches over carpal bones of hands covering them and forming the roof of the carpal tunnel. Attaches to tubercle of scaphoid and ridge of trapezium and on other side to the pisiform and hook of hamate. Is continuous with the Palmer carpal ligament and Palmer aponeurosis.

Question 181

Guyons canal

Answer 181

Semi rigid longitudinal canal in wrist allowing passage of ulnar artery and nerve into hand

Question 182

Define tendon sheath in hands

Answer 182

Layer of synovial membrane around tendon Permits stretch and non adherence to surrounding fascia. Two layers - synovial (inner) and fibrous (outer). In the hand begin at end of metacarpal bones and extend to distal phalanxes. Surrounded by annular ligaments (rings) and cruciate pulleys (criss cross formation). Three cruciate per finger, five annular. Annular often prone to injury. These help bind tendon to finger for movement, strength and protection from bowstringing.

Question 183

Define vinculae in hand

Answer 183

Connecting band of tissue such as that attaching a flexor tendon to bone of finger or toe Each tendon of finger has two sets - longus and brevis.

Question 184

Extensor hood

Answer 184

Fibrous tissue in finger running up and over extensor tendon of finger Many tendons converge here strengthening tissue such as interosseous muscle

Question 185

Pollical Palmer interosseous

Answer 185

Very debated origin and function Present in 85% population, in addition to adductor pollicis of the thumb? Can have multiple slips. Theories- Extra head of FPB behaving as an adductor or additional head of APB? Unknown. Also seen in primates thought to be part of evolutionary trait?

Question 186

Functions of structures in the head

Answer 186

``` Neural mechanisms Vision Hearing Respiration Smell Digestion ``` To carry these out head must be supported and must be able to travel through neck to continue function eg respiratory, digestive systems etc Also need to be flexible for visual and auditory systems The head is complex containing 28 bones, many which arise from several ossification centres and are formed wholly or in part by mesenchymal and endochondral origin.

Question 187

The skull

Answer 187

Cervical region of vertebral column supports the head allowing movement without compromising functioning of soft tissue which pass through the neck - pharynx, larynx, nerves etc Many structures either pass through or are attached to base of the skull Pharynx and larynx attach to base, carotid artery and many nerve plexuses pass through it spinal cord passes through using the foramen magnum - hole in base of skull where spinal cord passes.

Question 188

Supporting the head

Answer 188

Stability of cervical region of Vc is essential to function of head and neck Stability depends on integration of structures in neck supporting it

Question 189

Atlanto-occipital articulation

Answer 189

Occipital condyles lie on anterior margin of foramen magnum. Project down and articulate with lateral masses of the atlas. Each condyle is convex from anterior to posterior and also slightly from side to side. Atlas has concave articular facets on superior surface which in conjunction with occipital condyles allow for nodding movement Slight lateral concavity allows for slight lateral tilting. Lateral flexion is very slight (3°) but there is no lateral flexion between C1/2. The occipital condyles move posteriorly and are limited by tension of capsule and ligaments. In extension condyles slide anteriorly and limited by approximation of posterior bony areas.

Question 190

Atlanto-occipital joint movement

Answer 190

Inferior facets of atlas are slightly convex and flattened as are superior facets of axis There is third synovial articulation between two bones anteriorly Flexion and extension and rotation are possible at these joints Articulation on lateral facets roll and slide during flexion and extension During rotation odontoid stays put as ring formed by bone and transverse ligaments turns Consists of odontoid facet, superior and inferior facets and superior and inferior facet on lateral atlas. As atlas has no body all forces are generated between head and spinal column pass through lateral synovial joints. In atlanto-occipital joint also pass lateral. Thus joint capsule is very strong. Ligaments and muscles are needed to maintain positioning

Question 191

Balanced position of head

Answer 191

As occipital condyles are not placed in balanced position on base of skull head tends to tip anteriorly Many ligaments reinforce joints here and maintain integrity of joints and muscle action needed to keep head in balanced position with eyes forward

Question 192

Prevertebral muscles

Answer 192

Bilateral contraction of these actively flexes the neck while unilateral laterally flexes and rotates Extrinsic muscles : Sternocleidomastoid - unilateral contraction gives rotation, contralateral lateral flexion and extension. Bilateral accentuates cervical lordosis with extension of head and flexion of cervical column but if Column Is kept rigid it flexes the head. Trapezius - elevates, retracts and rotates scapula. With fixed shoulders bilateral contraction extends neck while unilateral produces flexion. Superficial intrinsic muscles - produce extension and rotation, lateral flexion to their side. Are both antagonist and agonist to extrinsic muscles. Deep posterior muscles - consists of short muscles running between occipital region and C1/2. Vital for fine tuning in determining position of head and maintaining integrity of joints at rest and movements as well as producing flexion, rotation, extension etc.

Question 193

Superficial intrinsic muscles of neck

Answer 193

``` Splenius capitus Levator scapulae Semispinalis capitus Ilio-costalis Splenius cervicis Longissimus capitus Semispinalis cervicis ```

Question 194

Deep posterior muscles of neck

Answer 194

Rectus capitus posterior major and minor Oblique capitis inferior and superior Interspinous

Question 195

Reflexes and neck movement

Answer 195

A prompt stereotyped reaction to stimulus in early days of life Number of reflexes are associated with neck movement present in early life but also continue into adulthood Many activities make use of these reflexes but they can be overridden Labyrinthine reflex - causes infant and adult to straighten arms and legs in response to looking upward. Neck reflexes are most important in sports skills. Flexed head favours elbow flexion while extended favours elbow extension useful in handstands etc. Strong head movements can help maintain spinning. To resume normal body alignment head corrects position and body automatically follows. If head is turned away from side of extended arm it can cause the arm to flex. Motor activity is learned and can overcome this eg in a learned dive both arms are extended but the neck is flexed.

Question 196

Renal arteries anatomy

Answer 196

Less than 1% body mass but use up 10-20% total blood volume Right longer than left due to crossing IVC posteriorly (left vein longer than right due to crossing Aorta anteriorly) They split into anterior and posterior branches Cortical branches stem around pyramids in the cortex, actuate arteries around pyramids in the medulla. Variations - found in 30% people Accessory arteries enter via the hilum from the aorta while aberrant arteries go directly to the poles of the kidney usually the bottom end. Accessory and abberant arteries are typically from the aorta but can stem from the coeliac trunk, SMA, IMA, middle coeliac or middle sacral artery. Aberrant arteries found commonly between T11-L4. Supply the kidney without entering its hilum.

Question 197

Ectopic kidney

Answer 197

Congenital disease where the kidney is ectopic - located in the wrong place. Typically the pelvis. Kidney blood supply often from the common iliac arteries in these cases. Occurs around week 8 of development Often asymptomatic but can increase risk of miscarriage, urine infection or stones Diagnosed by cystoscopy If problems arise then can have a nephrectomy to remove the kidney. Blood supply from surrounding area due to lack of migration eg iliac arteries if in pelvis.

Question 198

Multi-cystic kidney dysplasia

Answer 198

Congenital condition sporadically inherited patterns Caused by Abnormal differentiation of renal parenchyma and failure metanephric tissue to link with the metanephric duct collecting tubules leading to blind ducts. These can fill with fluid causing multiple cysts. Tubes often 1mm-1cm long. If bilateral the foetus is miscarried due to no functioning kidney If unilateral the good kidney will have hyperplasia growing twice the size twice as effective to compensate.

Question 199

Duplicated ureter/duplex collecting systems

Answer 199

Two ureters per kidney develop in 1% the population Ureters develop in the fourth week from the mesonephric duct. This can either arise twice or can split. Complete duplex caused by mesonephric duct arising twice forming two ureters Partial formed from split duct where ureter splits at the bladder - not two whole separate ureters. Most common in Caucasians and women. However might be possible women are more prone to urine infections and therefore get diagnosed more as often asymptomatic so males just may be undiagnosed.

Question 200

Wilms disease

Answer 200

Aka nephroblastoma very common kidney tumour in children, rare in adults. Caused from blastema cells in development not regressing and persisting causing genetic changes forming a nephrogenic rest Can form benign lesion called adenomatoid rest or cancerous form called nephrogenic rest/Wilms disease.

Question 201

Renal agenesis

Answer 201

Condition affecting 0.01% where newborn is missing one or both kidneys Bilateral is usually fatal without dialysis while unilateral is survivable Caused by faulty interactions between the ureteric bud and metanephric mesenchyme so the ureteric bud fails to develop. Related to RET and GDNF genes as these are the inductors of the ureteric bud. Diagnosed by MRI, prenatal ultrasound Can have few limitations/asymptomatic depending on healthy kidney. Often suffer potter sequence - atypical appearance of baby due to development issues, clubbed feet, pulmonary hypoplasia, cranial abnormalities etc.

Question 202

Scapolunate instability

Answer 202

Scapholunate ligament important for proximal carpal bone stability - rupture to this (caused by fush injury - falling onto outstretched hand) causing carpal bones to separate and become very unstable Called the terry Thomas sign.

Question 203

Common wrist injuries

Answer 203

Colle’s fracture - Fracture of distal end of radius resulting in upward displacement of radius and wrist deformity. Smiths fracture - aka reverse colle’s fracture, of the distal radius caused by direct blow to dorsal forearm or falling on flexed wrists. Barton’s fracture - fracture through articulating facets of radius involving the wrist joint itself. With dislocation of radiocarpal joint. Two types - dorsal and Palmer/ventral (reverse Barton’s fracture) with Palmer being more common. Die punch fracture - from axial loading force on distal radius is intra-articular fracture typically of lunate fossa which is depressed or impacted. Chauffeur’s/Hutchinson fracture - oblique fracture through the radial stolid process caused by compression of scaphoid bone against the radial styloid. Ulnar styloid fracture - almost never seen alone, usually paired with radial fractures as well. Scaphoid fracture - 60% of wrist fractures, very common, not easy to see and diagnose by consequences of missing it can cause long term wrist pain.

Question 204

Blood supply to scaphoid

Answer 204

Dorsal scaphoid branch - very important pierces bone proximally Volar scaphoid branch Superficial branch of radial artery Most common scaphoid fracture is thorough the waist of the bone causing disruption to dorsal scaphoid branch so proximal bone dies while distal part survives due to blood supply not being damaged

Question 205

Finger fractures and injuries

Answer 205

Very strong bones able to resist reasonable longitudinal stresses but not so much lateral stresses Bennett’s fracture - fracture of base of first metacarpal bone, intra-articular And is most common fracture of thumb. Nearly always accompanied by subluxation or frank dislocation or CMC joint. Reverse Bennett’s fracture is of the little finger. Mallet finger - loss of extension of distal phalanx caused when tendon to straighten finger is damaged. Caused when object forcibly bends tip of finger or thumb tearing the tendon. Commonly also breaks section of bone.

Question 206

Hook of hamate fracture

Answer 206

May go undiagnosed until attritional rupture (gradual wearing down, weakening) of long flexor tendon of small finger

Question 207

Volar plate rupture in hand

Answer 207

Around MCP joints of fingers - rupture can allow excessive extension of the finger Can also cause swan neck deformity, hyperextending joint and flexion of other joints. Also seen in arthritis and rheumatoid arthritis.

Question 208

Osteoarthritis if hand

Answer 208

Osteophytes can form on joints of fingers Distally are called Heberdens node and proximally called Bouchards node. Causing movement pain etc.

Question 209

Gamekeeper (skiers) thumb

Answer 209

Partial or complete rupture or ulnar collateral ligament of MP joint causing hyper mobility commonly caused by ski pole injuries etc.

Question 210

Rupture of flexor digitorum profundus

Answer 210

Forced extension of DIP joint during active finger flexion usually ring finger because of limited independent extensibility Causes avulsion fracture of FDP tendon from its insertion into volar lip of distal phalanx

Question 211

Boutonnière deformity

Answer 211

Disruption of extensor mechanism of finger or toes - nearest knuckle PIP joint is permanently bent toward the palm while farthest joint DIP is bent away. PIP flexion with DIP hyperextension Treated with tendon reattachment

Question 212

Trigger finger

Answer 212

Occurs in any digits finger is held in fixed flexion apart from quick flick into extension. Caused by inflammation of tendon or fibrous flexor sheath so cant fit into opening of fingers causing movement difficulties

Question 213

DeQuervains tenosynovitis

Answer 213

Inflammation of tendons on side of wrist at base of thumb - extensor pollicis brevis And abductor pollicis longus tendons. Flexion is difficult so is tested by making clenched fist. Causes pain. Finkelsteins test.

Question 214

Infections of hand

Answer 214

Tissue space infections - many spaces in wrist joint such as Parona’s space which can become inflamed in infections causing pain from compression and rubbing on tendons and nerves etc. Palmer spaces can also become inflamed. Caused by piercing into spaces eg nails into hands etc where infections can then develop. Lots of swelling, pain, inflammation. mid Palmer space more commonly affected than thenar space. Dupuytrens contracture - condition where one or more fingers are permanently bent in flexed position. Usually begins as small hard nodules just under skin of palm. Then worsens until fingers can no longer be straightened. Palmer aponeurosis inflamed and infected and fibrosed causing shortening of bands of Palmer aponeurosis causing this flexion. Very disabling.

Question 215

Injuries to cervical spine

Answer 215

Most common symptoms are pain and stiffness Can prolapse and spondylosis may occur as in rest of spine Occur due to vulnerability of region. Is most mobile part of spine so prone to dislocation, fractures. Spinal cord in this region may be compressed or transected. Many injuries here are immediately fatal. Age related changes occur such as osteoporosis leading to compression fractures and changes in alignment of spine. Examples Atlas fracture Displacement of atlantoaxial joint Compression of vertebral body Flexion subluxation and dislocation Extension subluxation

Question 216

Fractures atlas

Answer 216

Vertical force through skull may fracture the atlas - compression injury. Bony ring forced open by impact of occipital condyles Usually little displacement so spinal cord escapes serious injury. Support by collar or halo for three months is usual treatment

Question 217

Displacement of atlantoaxial joint

Answer 217

Uncommon as direct result of trauma but may occur in association with rheumatoid arthritis which increases laxity by stretching transverse ligament leading to dislocation

Question 218

Fracture of the Dens

Answer 218

Stability of atlanto occipital joint depends on anterior arch of atlas and integrity of transverse ligament Stability might be lost if either elements are damaged Displacement of the Dens posteriorly is fatal If no initial displacement then halo cast is treatment to immobilise joint Cases where fracture doesn’t heal and only fibrous union can be stable but if not fusion is needed surgically

Question 219

Compression of vertebral body in cervical spine

Answer 219

Severe flexion may result in compression of vertebral body Due to arrangement of trabeculae the compression is most marked anteriorly resulting in wedging Posterior ligaments usually remains intact so this fracture is stable and unlikely to result in injury to spinal cord

Question 220

Burst fracture in neck

Answer 220

Uncommon variant of wedge compression fracture. Force is transmitted along vertebral bodies while spine is straight. Force will rupture end plates and IVD which are forced into body giving appearance of having burst out in all directions Spinal cord may be damaged by posterior fragments Posterior ligaments eg interspinous and supraspinous remains intact

Question 221

Flexion subluxation and dislocation in neck

Answer 221

Vertebra displaced forward on adjoining vertebra and usually occurs in lower area of neck Injury may be bilateral or unilateral depending on origin of force causing injury Spinal cord usually escapes injury but if ligaments damaged and don’t heal then spinal fusion is recommended

Question 222

Extension subluxation in neck

Answer 222

Uncommon injury where anterior longitudinal ligament ruptured by severe trauma Anterior parts of vertebral bodies forced apart Spine is unstable in extension and neck must be supported in neutral or slightly flexed position

Question 223

Bone remodelling in osteoporosis

Answer 223

``` Osteoclasts attach to Surface of bone Bone reabsorption and deep cavity forms Osteoblasts enter cavity Osteoblasts lay down smaller amount of bone Bone reabsorption exceeds bone formation ```

Question 224

Kyphoplasty and vertebroplasty

Answer 224

Percutaneous techniques to restore vertebral body anatomy Initially developed for osteoporosis and tumoral lesions use has been extended to treat compression fractures Balloon inflated to restore shape of vertebral body then filled with cement Vertebroplasty injects cement directly into body- leakage seems to be minimal as trabeculae are compressed by cement and so prevent leakage Can also use acrylic filling In addition to treating osteoporosis can be used for fractures of younger patients restoring anatomy but not all fractures are suitable for this

Question 225

Lumbar plexus

Answer 225

``` Very variable T12-L5 nerves contribute - really only to L3 as after that is mostly sacral plexus but is hard to distinguish and very variable Subcostal nerve t12 Iliohypogastric t12-L1 Ilioinguinal - could say this is branch of iliohypogastric Lateral cutaneous nerve of thigh L2-3 Femoral nerve L2-4 Genitofemoral nerve t12-L1 Accessory obturator nerve L3-4 Obturator nerve L2-4 Part of sciatic nerve ```

Question 226

Iliohypogastric and ilioinguinal nerves

Answer 226

Huge variation but usually L1(can be low as L3 origin) travels laterally over iliac crest gives off cutaneous branch Sits between rectus abdominis and oblique aponeurosis Supplies cutaneous and motor and sensory skin around genitalia No agreement on what exactly it supplies - likely highly variable Ilioinguinal - comes laterally to inguinal canal through lateral wall, motor and sensory innervation runs along canal and exits via superficial inguinal ring. Becomes cutaneous to anterior third of scrotal wall in males or labia majora in females and medial thigh.

Question 227

Genitofemoral nerve

Answer 227

Divides into femoral and genital branch Femoral supplies skin at thigh and genital joins lateral wall of inguinal canal sits underneath internal oblique muscle exits the superficial inguinal ring hidden by external and cremasteric fascia. Supplies cremaster muscle - contracts testes for temp control for spermatogenesis Protected nerve not squashed by muscle etc

Question 228

Femoral nerve

Answer 228

Gives rise to saphenous nerve, lateral femoral cutaneous, and supplies most muscles and skin of thigh, leg and foot. articulator branches to hip and knee Origin L2-4 Large distribution sensory supply to skin and motor to anterior thigh. Well protected nerve travels through femoral triangle But is subject to compression from muscles or growths etc. Can be overstretched from hyperextension

Question 229

Obturator nerve

Answer 229

Articulate branches to hip and knee Posterior and anterior branches posterior Supplies adductor Magnus and gives off branch to knee Posterior supplies, pectineus, gracious and adductor longus And gives if branch to hip

Question 230

Innervation if adductor Magnus

Answer 230

Divided into bundles of fibres AM1-4 4 is considered hamstring part. Although hamstring portion supplied by tibial nerve there is also some with dual innervation from obturator nerve 28% subjects had dual innervation. Weird for muscles Most common arrangement is AM3 portion is also receiving double innervation from tibial nerve and posterior division of obturator nerve.

Question 231

Accessory obturator nerve

Answer 231

Variable if these are present 13% population have this Can arise from variable origin - L3-4, L2-4, L4,2, or from obturator itself Most common L3-4 Always gives branch to pectinous Descends along medial boarder of psoas major not passing through obturator foramen Terminated in three branches - pectineus, hip joint and adductor muscles via obturator nerve communicating branches.

Question 232

Sacral plexus

Answer 232

Plexus of pelvis and perineum from L4-S3 post divisions (3anterior 3posterior) Gives rise to tibial nerve l4-s3 quadratus femoris L4-5 Posterior division: Common peroneal L4-S2 Superior gluteal L4-S1 Inferior gluteal L5-S2 From anterior sacrum direct to muscle: before divisions (3anterior3posterior) all begin with P!! Piriformis S1-2(3) variable Pudendal s2-4 constant nerve of perineum and external genitalia innervation. Posterior femoral cutaneous s1-3 Perforating cutaneous nerve s2-3 Perineal branch s3/4 Nerve supply to pelvic floor Pelvic splanchnic s2-4 carry parasympathetic nerves into pelvis

Question 233

Posterior cutaneous nerve of thigh

Answer 233

Arises partly from dorsal divisions of 1/2 and from ventral divisions of 2/3 sacral nerves Posterior thigh, popliteal fossa supplied cutaneous below glut maximums muscle.

Question 234

Normal lumbosacral trunk variations

Answer 234

Many post fixed and pre fixed variations - literature defines these differently and so results in inconclusive data Often when L4 furcal nerve is weak there’s extra contribution from S5 but this isn’t a post fixed plexus Furcal - fork nerve defining pre and post fixation or plexus Post fixed plexus do have tendency to have contribution from S5 Can have in between both unsure how to classify

Question 235

Female and male pelvis

Answer 235

Female pelvis is boarder and shorter than males due to the sciatic notch and subpubic angle differences -90° and above is female Sacrum is shorter and wider in females and the ilium is longer

Question 236

Sacrum ossification

Answer 236

Begins to fuse at puberty around 17/18 and ends at 23 but this is variable

Question 237

Sacroiliac joint with age

Answer 237

Ilium - in childhood the surfaces are smooth and there are gliding movements in all directions but after puberty the surface configuration changes and movement is restricted During pregnancy the ligaments become softened and mobility increases Joint surface in young displays a fine granular texture with a well defined outline and no porosity As age increases the joint loses its well defined outline, becomes more rugged and the surface more porous.

Question 238

Sacroiliac joint ligaments

Answer 238

Stability of the joint is very important - the forces of body weight tend to separate the sacrum and ileum but this is resisted by the sacroiliac, sacrospinous and sacrotuberous ligaments and they also prevents forward rotation of the sacrum. Ligaments - some of the strongest in the body: Interosseous sacroiliac ligament - short strong fills in space behind and above joint. Fibres run in variety of directions forming superficial and deep layer. Sacrospinous ligament - triangular ligament arising from lateral aspect of sacrum, coccyx and inferior part of sacroiliac capsule and attaching to iliac spine. Also provides support to pelvic floor Sacrotuberous ligament - broad ligament from posterior superior iliac spine to upper part of coccyx consists of three bands and resists movements at the joints during flexion and extension of trunk Iliolumbar ligament - strong ligament connecting transverse process of fifth lumbar (sometimes fourth) to ileum. Fibres pass anteriorly to sacroiliac joint enhancing stability. Upright position plays important role in preventing fifth lumbar vertebra from sliding forward into sacrum.

Question 239

Sacroiliac joint movement

Answer 239

During flexion and extension of trunk the sacroiliac moves approx 1-2° and is result of mechanical forces acting on sacrum during load bearing and locomotion. Surrounding ligaments and muscles counteract this movement Sacroiliac joint is designed to act as stress relieving joint During gait cycle it’s subject to twisting forces which if it were a solid ring it would crack Such cracking can occur in the elderly is joint fuses

Question 240

Sacroiliac joint dysfunction

Answer 240

Chronic back pain is common condition and the number one cause of disability - sacroiliac joint is a known source of low back and lower extremity pain is presenting patients There are many possible locations for the pain which makes diagnosis difficult. Cause of 10-60% back pain Standard method of investigation is controlled anaesthetic blocks but these are invasive, expensive and difficult to interpret. Many causes of SIJ pain with 65% attributed to trauma and cumulative injury 35% idiopathic and remainder to aged related changes Increasing age may lead to fibrosis adhesions forming across joint leading to loss of synovial cavity. Occurs in males and females in about 24% people In addition to fusion at SIJ hyper mobility mainly as result of increasing age which can also occur as result of pregnancy or trauma may cause strain on joint. In such cases pelvic belt has been suggested to aid stability but there’s a lack of evidence that compressive forces forces were exerted on the SIJ or pelvis via the belt Under moderate tension many patients reported decrease in pain. Lax ligaments may allow joint surfaces to override each other and become locked in abnormal position Although not necessarily painful in itself it may lead to strain on other pelvic joints and lumbar spines

Question 241

Pubic symphysis

Answer 241

Stability of pelvic ring depends on pubic symphysis as well as sacroiliac joints and all movements of sacroiliac joints will affect pubic symphysis Is secondarily cartilaginous joint therefore ends of bones are covered in hyaline cartilage and separated by fibrocartilage There is a slit like cavity in the fibrocartilage but no evidence of synovial membrane Surrounded by ligaments which are strongest inferiorly Functionally is resits tension, shearing and compression Outline of shape changes throughout adult life and has been used to age adult skeletons Bony ridges of the young are replaced in older ages by smoother surface

Question 242

Superior and inferior pubic ligaments

Answer 242

Superior pubic ligament attached to pubic tubercle on either side of joint Strength and significance of ligament is still debated Inferior pubic ligaments spans pubic rami and again it’s significance is disputed

Question 243

The disc of the pelvis

Answer 243

Fibrocartilaginous disc adapted to withstand compressive and tensional forces and is wedged shaped Has been compared to IVD as the outer fibres are said to resemble the annulus There’s a cleft present in the disc whose lining and contents are much debated with some suggestions may be synovial in nature Origin of cleft is debated as to whether it’s present in the new born or whether it’s a result of degeneration

Question 244

Pubic symphysis movements

Answer 244

Healthy pubic symphysis is resistant to separation | During weight bearing on one leg there is forward displacement of pubic bone on weight bearing side

Question 245

Pelvis and pregnancy

Answer 245

Pelvic joints and ligaments are more relaxed in pregnancy and capable of more extensive movement Increases in diameter but extent is very variable Sacroiliac joints permit more rotation and slightly changes the diameter of the pelvis which puts greater strain on ligaments Following childbirth the ligaments tighten again but may lock the joint in a more rotated position leading to pain as the ligaments are under greater tension. Backward rotation of ilium on the sacrum is the most common and usually unilateral

Question 246

Transversus thoracis

Answer 246

Most anterior muscle of inner layer of thoracic wall Thin band of muscle and tendon arising from lower posterior surface of sternum, posterior edge of xiphisternum and costal cartilage of lowest 3-4 ribs at their sternal end Diverges supero-laterally to attach by slips to the underside of the 2-6th costal cartilages Is morphologically identical to the transversus abdominis muscle Blood supply from anterior and posterior intercostal arteries Innervated by intercostal nerves Acts as accessory muscle for respiration pulling ribs cranially supporting expiration

Question 247

External intercostal muscles

Answer 247

Eleven muscles each side of ribs located in intercostal spaces expanding the transverse dimension of the thoracic cavity in inspiration Are the outermost layer of the three intercostal muscles and arise from lower boarder of rib above the respective intercostal space Fibres run in downwards, forwards and medial direction and insert into outer lip of superior boarder of rib below. At insertion they end in thin anterior intercostal membranes that continue towards the sternum. Anteriorly the lower muscles become continuous with external oblique muscles in the anterolateral abdominal wall Blood supply from anterior and posterior IC arteries and veins and internal thoracic vein. Innervation from intercostal nerves T1-11 Acts to expand thoracic cavity in the transverse dimension and causes influx of air into the lungs during inspiration. Stronger than internal intercostals

Question 248

Internal intercostal muscles

Answer 248

Located in intercostal spaces, reducing the transverse dimension of the thoracic cavity during expiration Middle muscles of the intercostals and arise from the costal groove of the rib above Fibres run in downwards, backwards and lateral direction perpendicular to external intercostal muscles and insert into the superior boarder of rib below. Anteriorly the lower muscles become continuous with the internal oblique muscles in the anterolateral abdominal wall. Blood supply from anterior and posterior ICArteries And internal thoracic vein and ICVeins. Innervation from ICnerves Acts to reduce volume or thorax in transverse dimension expelling air from lungs during expiration.

Question 249

Innermost intercostal muscles

Answer 249

Muscles of expiration reduce thorax volume Contract along with internal intercostal muscles Most deep of the intercostals arise from inner margin of costal groove of rib above fibres running downward, backwards and lateral like internal ICM and perpendicular to external ICM and insert into superior boarder of rib below. Some describe muscles continuing over several ribs as opposed to just one. Become continuous anteriorly with the subcostal muscles and posteriorly with transversus thoracis muscles. Blood supply anterior and posterior ICA and ICV and internal thoracic veins. Innervated by ICN Act to reduce thorax volume in expiration

Question 250

Subcostal muscles

Answer 250

Variable anatomy and forms upper part of ICM group Lies on deep surface of innermost ICM In posterior chest near the angles of ribs usually running over 2-3 IC spaces Most common In upper 1-4 and lower 9-11 IC spaces Studies show a mean of 5 subcostal muscles per person and they have either band like or fans like shape

Question 251

Sternalis muscle

Answer 251

Uncommon anatomic variant of the chest wall musculature and is of uncertain etiology and function. As well as variable shape and margins It’s importance is that it shouldn’t be mistaken for a pathological lesion Cadaveric studies show muscle is present in 1-8% of both sexes and is twice as often unilateral as if is bilateral Runs from jugular notch inferiorly to approx. The caudal inferior aspect of the sternum. Is found adjacent to the medial edge of pectoralis major.

Question 252

Anterior intercostal arteries

Answer 252

1-6 anterior ICA arise directly from lateral aspect of internal thoracic artery 7-9th arise from musculophrenic artery, branch of the internal thoracic In each IC space the artery divides into paired branches - the larger courses laterally in the upper aspect of respective IC space between the internal and innermost ICM below the ICV and above the ICN protected by costal groove of rib above. Smaller collateral branch descends into lower aspect of respective ICS and courses laterally between the internal and innermost ICA. Not offered protection by the rib above. In the two inferior spaces 10/11 the anterior ICA is absent with the posterior ICA supplying each space solely Branches as these arteries course laterally within ICS they give off variable numbers of small perforating cutaneous branches. In the lateral aspect of thoracic wall, the artery anastomoses with branches of the posterior ICA. Also supply the skin within the ICS and parietal pleura

Question 253

Posterior ICA

Answer 253

First two ICS supplied by superior ICA and remaining nine supplied by separate branches from the descending thoracic aorta Right side are longer as aorta is to the left of the midline. They pass in front of the vertebrae and behind the azygos venous system, oesophagus and thoracic duct. Left side arteries run posteriorly adjacent to the vertebrae and enter into the ICS Superior ICA is descending branch of the Costcervical trunk, which arises from the second part of the subclavian artery Enters the thorax anterior to the neck of the first rib with the sympathetic trunk on is medial side. Divide into anterior and posterior rami. Anterior ramus runs along costal groove accompanied by ICN and vein. Then divided into four branches : collateral IC, lateral cutaneous, mammary and muscular. Also branches that anastomoses with other vessels to supply the spinal cord and soft tissue structures of the back. Also supplies the skin in ICS and parietal pleura.

Question 254

Supreme ICA

Answer 254

Aka superior ICA. Formed as result of embryological development of the intersegmental arteries. These are paired structures of the upper thorax normally provide blood to first and second ICA. Supreme ICA is traditionally thought to form as an anastomoses between 8-9th intersegmental artery branches and the ipsilateral subclavian artery. In variation new research suggests supreme ICA is actually derived from 7-8th intersegmental arteries although it remains that it’s formed by the two intersegmental arteries caudal to the subclavian formation. After involution if portions of the intersegmental arteries between the aorta and the anastomoses, the supreme intercostal artery serves as the principle source for arterial blood flow to the posterior ICA of 1/2nd ribs. Variant anatomy - notes variation of origin and distribution. Usually originated from costocervical trunk but can also from the thyrocervical trunk or subsequent branches such as the dorsal scapular artery or inferior thyroid artery. Additional origins include axillary artery, second ICA or vertebral artery where it passes through transverse foramen of the 7th cervical vertebra and then inferiorly passing posterior to the ribs. There’s been cases of the left supreme ICA originating from the internal thoracic artery or as a fourth branch off the aortic arch. Distribution varies from expected region of first and second ICS which occurs in approx 72% cases to involve the 2/3rd spaces in approx 8% of cases while approx 20% involve only first ICS Some research suggests anatomically normal course may only involve the first ICS, in these cases the artery is diminutive when compared to arteries feeding both the 1/2nd spaces.

Question 255

Venous drainage of thoracic wall

Answer 255

Anterior ICV - originate from ICS inferior to anterior aspects of their respective ribs and drain into the internal thoracic and musculophrenic veins Posterior - originate from ICS just inferior to posterior aspects of respective ribs. Right side 4-11th posterior and subcostal veins drain into the azygos while 4-7th (8th) left side drain into the accessory hemiazygos vein. The 8-11th left sided posterior intercostal and subcostal veins drains into the hemiazygos vein. Supreme ICV drain the first ICS posteriorly opening into the vertebral or brachiocephalic veins. Superior ICV posterior 2/3rd ICS are drained by their respective posterior ICV into the superior ICV into the azygos and brachiocephalic veins in the right and left sides respectively. Variant anatomy - superior ICV May additionally drain the 4th ICS and the accessory hemiazygos vein may drain the left 8th ICS posteriorly.

Question 256

superior ICV

Answer 256

Highest veins drain into first space on each side and joins brachiocephalic vein. They have no valves - important in case of cancerous spread Left superior ICV drains the left posterosuperior hemithorax and it’s considered to be part of azygos venous system even though it doesn’t directly drain into the azygos Formed by union of 2-4th left posterior ICV Courses superiorly to left of the midline and arches posteriorly lateral to the aortic arch to drain into the left brachiocephalic vein Typically communicates with accessory hemiazygos vein. Tributaries left 2nd and 4th posterior ICV. Variant anatomy - might not communicate with accessory hemiazygos in 25%. Left azygos or hemiazygos lobe may be caused by aberrant left superior ICV. Hemiazygos and accessory hemiazygos veins may drain directly into the left brachiocephalic vein via the left superior ICV. May be enlarged in presence of congenital azygos, hemiazygos or accessory hemiazygos vein absence (rare)

Question 257

Branches of subclavian in relation to scalene muscles

Answer 257

``` VIT C D medial to laterally Vertebral Internal thoracic Thoracocervical Costocervical Dorsal scapula ```

Question 258

Structures supporting the pelvic viscera

Answer 258

Uterosacral fold containing uterosacral ligaments Cardinal transverse ligaments Uterovaginal fascia The ligaments tie the cervix of the uterus and fornix of the vagina to the lateral and posterior walls of the pelvis Cardinal ligaments run from the base of the broad ligament and uterosacral ligaments run to the sacrum on either side of the rectum.

Question 259

Perineum

Answer 259

A region beneath the pelvic diaphragm divided into the anal and urogenital triangles Urogenital diaphragm - perineal membrane is flat fibrous sheet running between ischiopubic rami and stops short of the pubic symphysis where arcuate ligament joins the gap between two pubic bones. There’s a foramen for the urethra and vagina in female and posteriorly membrane inserts into the perineal body. Levator ani lies above the perineal membrane and between them is the external sphincter urethrae. Is a voluntary sphincter.

Question 260

Pelvic floor

Answer 260

The crura of the clitoris lies on the ischiopubic rami and are covered by the ischiocavernosus muscles. Anteriorly they fuse to form the body of the clitoris The bulb of the vestibule is also fused anteriorly and forms the gland of the clitoris but is divided posteriorly And lies either side of the vaginal and urethral openings.

Question 261

Adaptations of the uterus to pregnancy

Answer 261

Prior to it weights about 50-60g while at term this increases to about 1000g. Grows by hyperplasia and hypertrophy mostly hypertrophy in latter stages Uterine arteries also distend Body of uterus has highest concentration of smooth muscle cells while cervix has fibrous connective tissue with about 30% muscle tissue. Non pregnant size - plum. 6weeks egg, 8 weeks small orange, 12 weeks grapefruit. By 12 weeks uterus shifts forwards and up no longer pressing on bladder at 13 weeks ligaments stretch and by 14 weeks it may be pressing on bowel. By 25 weeks is size of football. May press on back and cause lower back pain by week 27 is close to rib cage preventing full lung expansion. Lying on right side may obstruct the IVC and aorta and by week 32 uterus is pushing on abdominal organs. By week 40 labour can occur at any time and contractions can start in uterus

Question 262

Adaptations of musculoskeletal system to pregnancy

Answer 262

During pregnancy there is substantial weight gain up to 18kg Uterus expansion causes shift in centre of gravity backward over the pelvis leading to increased strain on muscles and ligaments which may cause lower back pain Hormone relaxin limits womb activity at cervix prior to labour also increases laxity of ligaments throughout the body leading to a decrease in joint stability. Substantial amount of Ca Is transferred from mother to foetus during pregnancy and lactation most studies show this has little effect on skeletal mass but lactation does cause temporary decrease in bone mass usually restored 6 months post weaning Anterior abdominal wall expands to accommodate the foetus growth. Occurs at midline where extra skin and subcutaneous tissue is added. Muscle of wall is pushed laterally and limits degree of stretch. In final trimester when foetus is growing rapidly skin growth may not be able to keep up and becomes stretched and thin.

Question 263

Adaptations in systems in pregnancy

Answer 263

``` Uterus Musculoskeletal Position of viscera Mammary glands Cardiovascular system Respiratory system Kidneys and urinary system ```

Question 264

CV pregnancy changes

Answer 264

Blood volume CO Arterial blood pressure Systemic vascular resistance

Question 265

Plasma volume changes in pregnancy

Answer 265

Fluid retention accounts for 8-10kg maternal weight gain most expansion occurs in ECF especially plasma Retention of Na and increase in antidiuretic hormones Most Na is passed into the foetus. Plasma osmolarity decreases as does plasma oncotic pressure resulting in increase in glomerular filtration rate and development of peripheral oedema. Although increase in production of erythrocytes the plasma increase of 30-40% causes dilution and therefore haematocrit and haemoglobin conc falls. White cell conc mostly increases due to neutrophil rise. Mean values 2L non pregnancy compared to 3-4L pregnancy

Question 266

Vasodilation and pregnancy

Answer 266

Vasodilation is early characteristic of pregnancy and increasing heart rate is seen by fifth week Result is increased CO Heart rate continues to rise by 20th week CO has risen from 5-7L/min. By third trimester is 10-15 beats faster with increase in stroke volume of 10-20ml. Arterial pressure is reduced indicating decrease in vascular resistance in first half of pregnancy but gradually increases in third trimester Towards end of pregnancy the IVC May be obstructed decreasing venous return.

Question 267

CV pregnancy values

Answer 267

``` HR increases 10-20% SV increases 10% CO increases 30-50% MABP decreases 10% Peripheral resistance decreases 35% ```

Question 268

Respiratory changes in pregnancy

Answer 268

Growth of uterus causes 4cm elevation of diaphragm but increases in diameter of chest and flaring of ribs means total lung capacity only slightly reduced Due to cardiac changes there’s an increase in pulmonary blood flow and also tidal volume from about 500ml to between 650-700ml and a decrease of 15-20% in pCO2 and a slight increase in PO2. There’s small increase in vital capacity 100-200ml and increase in inspiratory capacity from approx. 2200-2500ml. Residual capacity is decreased. Respiratory rate remains unchanged at between 16-18 breaths/min. O2 consumption is increased by 20% to cope with increased metabolic demands of mother and foetus and consequent increase in CO2.

Question 269

Renal function in pregnancy

Answer 269

Vasodilation occurs due to relaxation of smooth muscle by progesterone increase In the gut this leads to delay in gastric emptying and colonic motility while urinary tract becomes dilated Vasodilation reduces blood pressure and increases blood flow which in the kidney results in increased glomerular filtration rate 50% and increases clearance of substances from blood stream Action of progesterone dilates the ureters further enhanced by the enlarged uterus pressing on the ureters as they cross the pelvic brim and obstructing flow.

Question 270

Parturition

Answer 270

Labour during which the foetus, membranes and placenta expelled from the uterus Divided into three stages - commenced with regular painful contractions of uterus lasting for many hours and ends in full cervix dilation. Follows full dilation of cervix and ends with complete delivery of the baby and lasts for less than two hours Expulsion of placenta and membranes and lasts for only a few minutes

Question 271

Uterus in partuition

Answer 271

For the most part in pregnancy is relaxed an increases in size to accommodate foetal growth. As parturition begins it contracts regularly and forcibly and the cervix progressively effaces and dilates allowing foetus to descend through birth canal. May be result of increased sensitivity of myometrium to stimulation. Thought to be to do with balance between quiescence and contractility of uterus. In non pregnant the stimulators Ca and inhibitory CAMP are balanced while pregnant is weighted toward inhibition by Gas expression while onset of labour reduces Gas and increases stimulators Ca.

Question 272

Phase one partuition

Answer 272

Dilation of cervix starts slowly becomes more rapid. Consistency of cervix becomes softer and changes in shape from cylinder to funnel with very thin edges. Softness due to increase in vascularity and fluid content. Foetal head passes down birth canal widest I’m transverse direction at inlet but anteroposterior In outlet therefore baby must rotate. Head is forced into flexion and moves into the gutter made by levator Ani causing rotation. Space is narrow and passage of head is aided by passing of frontal and occipital bones under parietal bones and one parietal under the other

Question 273

Phase two partuition

Answer 273

Cervix fully dilated and well flexed head is in occipitoanterior position and as it descends and becomes more visible from outside Further process leads to crowning of foetal head followed by forehead and face Head now rotates through 90° so that occiput faces laterally Shoulders now enter brim of pelvis with biacromial diameter sitting transversely Shoulders then rotate to present anterioposteriorly and then are expelled Widest parts are now out and rest follows easily.

Question 274

Phase three parturition

Answer 274

Uterine muscle contracts and constricts blood vessels to prevent excessive bleeding Placenta usually separates from uterus at end of the second stage After short rest it contracts and placenta is expelled

Question 275

Diagnostic imaging of hip

Answer 275

X rays - low anterioposterior pelvis view CT scan - High resolution helical Bony anatomy MRI - stress fractures, transient osteoporosis, avascular necrosis, muscle injury, bursitis, loose bodies, effusion, synovitis, tumour Bone scan - poorly localised pain, tumour, stress fracture, transient osteoporosis, avascular necrosis.

Question 276

Pelvic foramen

Answer 276

Formed by sacrotuberous and sacrospinous ligaments. Piriformis passes through occupying most of the volume Greater sciatic foramen is wider in women then men Nerves passing through greater sciatic foramen - sciatic, superior gluteal, inferior gluteal, nerves to piriformis and obturator and quadratus femoris, pudendal nerve, posterior cutaneous nerve of thigh, perforating cutaneous nerve of thigh (through sacrotuberous ligament).

Question 277

Hip joint innervation

Answer 277

Femoral nerve via rectus femoris anteriorly Obturator nerve via anterior division inferiorly Accessory obturator nerve anteriorly Superior gluteal nerve superiorly and posteriorly Nerve to quadratus femoris posteriorly

Question 278

Blood supply to hip joint

Answer 278

Largely via the medial and lateral circumflex femoral arteries - branches of profunda femoris artery (deep femoral artery) they anastomoses at base of femoral neck to form a ring from which smaller arteries arise to supply the hip joint itself Medial circumflex femoral artery is responsible for majority of arterial supply (lateral circumflex femoral artery has to penetrate through thick iliofemoral ligament) Damage to medial circumflex can result in avascular necrosis of femoral head

Question 279

Hip joint development

Answer 279

Shape is nearly more hemispherical around time of birth and gradually changes from birth to young childhood (4years)

Question 280

Ligamentum teres femoris

Answer 280

Triangular and flattened Attached to anterosuoerior part of part of fovea capitis femoris and it’s base is attached by two bands one into either side of the acetabular notch. Between these it blends with the transverse ligaments. Ensheathed by synovial membrane varies greatly in strength by each subject Occasionally only the synovial fold is present and in rare cases both are absent. Tenses when thigh is semiflexed, abducted and rotated outward. Relaxed when adducted.

Question 281

Iliofemoral ligament and labrum

Answer 281

Ligament extends from ileum to the femur in front of the joint. It’s also referred to as the Y ligament. Tensile strength exceeds 350kg, stronger than ischiofemoral and pubofemoral ligaments and is the strongest in the whole body. Very important constraint for hip joint. Tense when pelvis is twisted posteriorly and ligament is twisted preventing trunk from falling back and maintaining posture without need for muscular activity. Also keeps femoral head pressed on acetabulum. Transverse part controls lateral rotation and adduction. Descending part limits medial rotation. Labral tear is insignificant Ligament tear and tearing both ligament and labrum is significant. Labral repair is insignificant Ligament and labral repair is significant. Therefore ligament is more important.

Question 282

Embryology development overview and lung formation

Answer 282

Week one implantation of zygote Week two inner cell mass divides into two layers epiblast and hypoblast - epiblast will become amniotic cavity. Week three gastrulation and primitive streak on epiblast, cells invaginate to form endoderm and mesoderm Week four neurulation folding forming neural tube and lateral folding forming fit and cephalocaudal folding take place Lung bud formation also takes place - respiratory diverticulum form, tracheoesophageal ridges form and fuse to make septum. Failure of this causes transoesophageal fistulas, presents as aspiration and respiratory difficulties at birth. Week five forms bronchial buds, right has 3 secondary bronchi and left has 2. Expansion into pericardioperitoneal canals takes place.

Question 283

Where does most of the thorax arise from

Answer 283

Mesoderm - connective tissue, lungs, ribs etc | Lung lining from the endoderm

Question 284

Trachea, bronchi and lung formation

Answer 284

Pleuroperitoneal and pleuropericardial folds separate periotoneal and pericardial cavities Mesoderm surrounding the lung forms the visceral pleura Mesoderm surrounding body wall forms parietal pleura Secondary bronchi divide into tertiary bronchi - 10 on right and 8 on left Maturation of lungs - terminal, respiratory bronchioles, alveolar sacs and terminal sacs develop. Increase in vascularisation and capillaries form. Increase number of terminal sacs. Type one cells thinner in close relation to capillaries. Type two cells form. Foetal breathing movements occur and aminiotic fluid is aspirated

Question 285

Maturation of lungs development periods

Answer 285

Pseudoglandular - 5-16 weeks Canalicular - 16-26 weeks Terminal sac - 26 weeks to birth Alveolar - 8 months to childhood

Question 286

Diaphragm development

Answer 286

4 main structures - septum transversum - central tendon Pleuroperitoneal membrane Dorsal oesophageal mesentery Body wall All from the mesoderm - parts of the liver also develop within the diaphragm and so create the bare area of the liver etc. 3 weeks - septum transversum forms as mass of mesoderm posterior to pericardial cavity 7 weeks - septum fused with pleuroperitoneal membranes and dorsal mesentery of oesophagus. Muscle fibres grow into dorsal mesentery to form crura. 9 weeks - inner layer of body wall forms peripheral diaphragm and myocytes form cervical segments 3-5 penetrate membranes to add muscular component to diaphragm

Question 287

Transpesophageal development

Answer 287

Week four of embryological development - tracheoesophageal ridges form and fuse to make septum. Failure of this causes transoesophageal fistulas, presents as aspiration and respiratory difficulties at birth.

Question 288

Lung development abnormalities

Answer 288

Hiatus hernia - weeks 3-9 diaphragm develops and fuses. failure or weakness of fusion between diaphragmatic components in development causing hernias, presents as hollow stomach in newborns. Transoesophageal fistulas - Week four of embryological development - tracheoesophageal ridges form and fuse to make septum. Failure of this causes transoesophageal fistulas, presents as aspiration and respiratory difficulties at birth. Pulmonary agenesis - failure of lung bud or primitive bronchi to form, often fatal. Week 4 of development. Hypoplasia of lung - restricted growth of lung bud leading to ill formation. Azygos lobe - fourth love present on lung due to malformation of azygos vein developing in the wrong place and punching top of lung leading to fourth lobe formation - functionally still the same as the upper lobe. Occurs in 1% population.

Question 289

Premature babies and surfactant

Answer 289

Premature babies before 6 months often have no surfactant as of yet and so present with respiratory difficulties If known the baby will be premature can administer maternal steroids or if Unknown insert endotracheal tube into newborn to give surfactant or administer O2 for less severe cases/until can have endotracheal tube.

Question 290

Hip pathologies

Answer 290

``` Snapping hip syndrome Bursitis Developmental issues Fractures and dislocations - uncommon due to strength of ligaments surrounding it Arthritis Infections and tumours Muscle injury Nerve lesions ```

Question 291

Nerves of the hip

Answer 291

Femoral - L2-4 Obturator - L2-4 Superior gluteal - L4,5,S1 Nerve to quadratus femoris - L4,5, S1

Question 292

Hip pain diagnosis

Answer 292

Often need to check the knee joint as femoral nerve pain at the knee can translate as pain nearer the hip Many conditions give pain around the hip but this doesn’t mean it’s the hip joint causing the pain is much more commonly other reasons Such as extra articular muscular diagnosis, uronephritis or referred pain from the abdomen etc.

Question 293

Snapping hip syndrome

Answer 293

Internal snapping hip Common cause is suction within hip capsule occurs during flexion Iliofemoral ligament clicking over femoral head Psoas tendon snapping over iliopectineal eminence Tendon snapping over ASIS or AIIS external snapping hip; Glut max tendon or iliotibial band snapping over greater trochanter Contributing factors: right ITB, narrow Bi-iliac width, poor flexibility and muscle strength imbalance Most discomfort is from associated bursitis Bursography can be used to confirm and bursectomy or IT band recession can be used to treat. Iliopsoas and ITB are most common causes. Latter distinguished from the formed as is much more lateral and more palpable.

Question 294

Hip bursitis

Answer 294

Psoas bursitis - presents with inguinal pain radiating to femoral triangle. Extreme hip rotation while in flexion can elicit pain. Trochanteric bursitis - characterised by deep burning pain localised just posterior to greater trochanter can radiate down to lateral thigh Ischial bursisits - commonly occurs after direct trauma. Must rule out Hamstring tear, epiphysitis in skeletally immature patients and osteomyelitis - infection of the bone, not very common.

Question 295

Hip dislocation

Answer 295

Uncommon and needs significant force due to the femoral head sitting in such a deep socket and supported by strongest ligaments in the body - therefore unlikely to become unstable and dislocate. Posterior dislocation - most likely of all dislocations as hip is least stable posteriorly. limb is foreshortened and medically rotated because lateral rotators are made ineffective. Leg is pulled up and back due to muscular attachments Danger to the nerves like sciatic at great risk of injury by femoral head Can use Shentons line to diagnose hip dislocation - imaginary line from inferior boarder of superior pubic ramus along inferior boarder of neck of femur. Should be smooth and continuous.

Question 296

Pelvic and hip fractures

Answer 296

Pelvic - any bones of the pelvis. Problematic as pelvis often well supplied with blood and so have high chance of haematomas and pushing pelvic organs causing further issues eg pubic ramus fractures Hip - refers only to the fractures of neck of the femur. Medial rotator muscles made ineffective causing lateral leg rotation. Transcervical fracture most common. Femoral neck fractures - limb fore shortened and laterally rotated because iliopsoas and gluteal muscles are made ineffective and pivot point where medial rotation occurs is altered so iliopsoas (not normally rotator) becomes medial rotator. Many classifications - subcapital (separates head from neck), transcervical (neck and head separated from body), intertrochanteric (between trochanters), subtrochanteric(below trochanters), fracture of greater trochanter and fracture of lesser trochanter. Further classification- type I fractures where bone ends impacted into one another, has best outcome as this facilitates re-growth and angiogenesis so femoral head survives. Type II - not impacted and are less stable however there’s minimal displacement of bones from normal position. Can displace further and worsen at any time however. Type III - complete fractures but only partial displacement Type IV - complete and total displacement two ends of bone completely separated - worse outcome possible avascular necrosis of femur head. Bryant’s triangle to determine how much displacement there is - palpate ASIS and greater trochanter and lines between this are triangle and degree of change from good hip to bad hip is level of displacement.

Question 297

Childhood hip disorders

Answer 297

birth - Developmental dysplasia 0-10- Perthe’s disease and irritable hip 10-15- slipped upper femoral epiphysis or rheumatoid arthritis Trendelenburgs sign often used for hip diagnosis - drop in bad side of hip as good side tried to compensate for lack of muscle on other side causing wonky pelvis.

Question 298

Developmental dysplasia of hip

Answer 298

1-3% infants born with this Flexion of the hip is the weakest position babies can lie in and increases chance of dislocation Genetic and cultural element involved - Chinese or North American Indian population hold babies swaddled with legs adducted so have higher rates of hip dysplasia while African population hold babies with legs abducted hugging parent so has less incidences. Barlows and ortolani test - abduct legs and if legs pop out of socket abduct 90° and can hear the ‘clunk’ of hip popping back in place means it’s a positive test for condition. Test regularly carried out in hospitals before babies are released.

Question 299

Legg-Calve-Perthe-waldenstroms disease

Answer 299

Problem in femoral head development causing avascular necrosis associated with abnormal clotting where clots aren’t absorbed or removed and this occludes vessels preventing blood supply Treated with de clotting agents to reduce change of happening can spontaneously disaster and head may then develop normally but unsure why this occurs Early sign of disease is mushroom shaped femoral head - sometimes needs surgical intervention to reduce flattening and maintain head shape encouraging bone growth and survival.

Question 300

Slipped upper femoral epiphysis

Answer 300

SUFE is later childhood and early teens most commonly as result of slipping of femoral epiphysis

Question 301

Arthritis/osteoarthritis of hip

Answer 301

Mostly above 60 rarely before 40 Younger if they have risk factors such as - trauma, congenital joint deformities, obesity, prior surgeries on hips can increase risk also. Women much more vulnerable but unknown why ratio 3:1 W:M.

Question 302

Pelvic floor dysfunctions

Answer 302

Risk factors - birth, vaginal deliveries, menopause, previous hysterectomy, hormone therapy, older age, gender(female), nutrition, functional bowel diseases, anxiety, IBS, drug abuse. Symptoms- urinary incontinence, urgency, difficulty initiating urination, uterine/vaginal vault prolapse, constipation, incomplete evacuation, faecal incontinence, rectal collapse.

Question 303

Pelvic floor - posterior part

Answer 303

Consists of three compartments - anterior, middle and posterior. Posterior - defaecation. Initiated by rectal distension as matter moves into rectum resulting in relaxation of internal anal sphincter. Muscles of pelvic floor relax and descend. As puborectalis relaxes the anorectal angle increases allowing anorectal canal to straighten. Abdominal muscles contract increasing inter ab pressure and anal canal opens emptying rectum usually under 30 seconds. Relaxation of ab muscles returns tone of pelvic floor raising it and allowing internal sphincter to close. Dysfunction - inability to coordinate these activities impairs elimination of faecal matter leading to either an increase in the evacuation time, retention of some material and reduction of anal canal width. Common problem in women following childbirth is rectocele, in conjunction with pelvic prolapse. Arises from loss of anterior rectal support from the rectovaginal septum - weakening of wall between rectum and vagina, causing vaginal displacement. Many females 80% may have small asymptomatic rectocele but larger ones may lead to vaginal prolapse and or obstructed defecation. Mesh based reconstruction of the rectovaginal septum is gaining support.

Question 304

Middle pelvic floor

Answer 304

Genital prolapse relates to descent of uterus and cervix into vagina and may extend to its opening (introitus) and is most commonly associated with prolapse of other pelvic organs and or the peritoneum and small intestine (enterocele) Collapse of the anterior wall of vagina is termed cystocele. There’s a loss of apical support as a result of damage to ureterosacral - cardinal complex. The bladder can become hyper mobile as a result of uterus lowering. Enterocele - herniation of peritoneal sac between vagina and rectum. Contains small bowel and or sigmoid colon making it a true herniation unlike other prolapses of the pelvic organs.

Question 305

Urinary incontinence

Answer 305

Anterior pelvic floor dysfunction Involuntary leakage of urine with stress incontinence occurring during exercise, coughing, sneezing etc Affects 200 million people worldwide likely to be a serious underestimate Prevalence may be as high as 55% Risk factors are pregnancy and childbirth and hysterectomy. Part of larger complex Called overactive bladder syndrome associated with frequency of urination and nocturia. 9.3% prevalence in women and less in men. Women with no children prevalence is 10.1%, caesarean 15.9% and vagina delivery 21%. Injury or damage to pelvic floor may lead to incontinence. During pregnancy the increase in intra ab pressure can lead to stress on the bladder and urethral sphincter. Weakness of pelvic floor muscle results in mobility of neck of bladder and urethra resulting in incompetence of sphincter Treated with surgery, incontinence pessaries or duloxetine. Reducing caffeine and fluids can also help. Pelvic floor exercises can also assist. Strengthening muscles contributes to closing. Main also be possible to train anal sphincter. In pregnancy training said to decrease incontinence prevalence. In women already with incontinence is said to improve for one year then decline but this may be result of having more children or not keeping up with exercises

Question 306

Pubic symphysis separation

Answer 306

Not common but may lead to considerable disability in long and short term Relatively soon after delivery patients complain of pelvic pain which increases severity and difficulty in getting up and walking Most cases the infant is larger than average Cause of separation may be rapid descent of foetal head, wedging head into pelvic ring, hyper abduction of thigh but may be other unknown factors Treatment is bed rest with elastic bandage placed around pelvis Situation may resolve quickly in 4-5 days but may take up to six months for reasonable resolution. In these cases continued fixation of the pelvic internally or externally is needed

Question 307

Accessory tendons of extensor hallucis longus

Answer 307

Present in 51-87% subjects May be one of two accessory tendons Attachment to capsule of first metatarsal phalangeal joint or base of proximal phalanx Function to stabilise MTPJ, correct pull of EHL bringing it in line with long axis of great toe.

Question 308

Knot of Henry

Answer 308

Superficial (plantar) crossing of flexor digitorum longus tendon obliquely over the flexor hallucis longus tendon in the mid foot at level of navicular bone Distally there can be connections between the two tendons. Best seen on coronal planes Is common site for tenosynovitis - inflammation of tendons synovial membrane presents as joint swelling, pain in affected joint, reddening of tendon, difficulty moving joint.

Question 309

Peroneus Quartus

Answer 309

Present in approx 15-20% of individuals preventing lateral ankle sprain

Question 310

Deltoid and lateral collateral ligaments

Answer 310

Deltoid - Medial ligament of tall rural joint. Attaches to apex and anterior and posterior boarders of medial malleolus. Composed of superficial and deep components. LC- anterior talofibular ligament ATFL connects front of talus to fibula. Calcaneofibular ligament CFL connects calcaneus to the fibula. Posterior talofibular ligament PTFL connecting rear of talus to the tibia.

Question 311

Sinus tarsi

Answer 311

Tunnel between talus and calcaneus contains structured contributing to stability of ankle and its proprioception but can get damaged in this tunnel. Trauma or overuse by repetitive strain can cause pain or injury to this area causing sinus tarsi syndrome. Causes instability or difficultly walking. Structures include cervical ligament, talocalcaneal interosseous ligament, lateral, intermediate and medial roots of inferior extensor retinaculum.

Question 312

Excessive pronation

Answer 312

Major causes of stress injuries - overloading structures in stance phase, prolonged probation into propulsive phase Results in loose foot - excessive mid foot motion, increased pressure on metatarsals and increased tibial rotation at knee Causes weakness push off - doesn’t allow foot to resupinate providing rigid lever, less powerful and less efficient force produced RIGID FOOT. Problems caused by this - plantar fasciitis, Achilles and posterior tibial tendonitis, sesamoiditis, hallux valgus, sinus tarsi and tunnel syndrome, metatarsalgia, medial knee pain.

Question 313

Rigid foot

Answer 313

Decreased mobility of calcaneocuboid joint and first ray causing weight absorption on first and fifth metatarsals Increased tension of peroneus longus and inefficient shock absorption occur Common injuries causing this - inversion sprains, tibial stress syndrome, perineal tendinitis etc.

Question 314

Lisfranc ligaments

Answer 314

Connects the superior, lateral surface of the medial cuneiform to the superior, medial surfaces of base of second metatarsal

Question 315

Development of the heart

Answer 315

Week 3- progenitor heart cells migrate from epiblast to mesoderm forming primary heart field Secondary heart field appears later and these unite to form cardiogenic region Cardiac Myoblasts appear. Blood islands appear which layer form vessels Week 4- due to folding of embryo, horse shoe shaped heart tube forms. This elongates and bends to form cardiac loop - cephalic portion bends ventrally, caudally and to the right. Caudal end loops in opposite direction from days 23-28. Formation of atrioventricular septa begins - Four atrioventricular endocardial cushions develop. formation of ventricular septa - Ventricles expand and growth of diverticular. Medial walls fuse to form muscular part of septum. Anterior endocardial cushion grows to close interventricular foramen. Week4-5- formation of atrial septa. Endocardial cushions develop in atrioventricular region. Septum primum forms in roof of atria. Ostium primum - small hole in inferior aspect. Cell death occurs in superior aspect - ostium secundum. Septum secundum grows down. This overlaps with free edge of ostium primum to form foramen ovale - a valve. Aortic arches arose from aortic sac - distal truncus arteriosus. Appear and disappear in succession and terminate in paired dorsal aorta - later fuses. Weeks 5- formation of atrioventricular septa continues - Anterior and posterior cushions fuse to form two atrioventricular canals. Each canal surrounded by mesenchymal tissues, which thin forming valves. Muscle tissues of valves replaced by connective tissue. Formation of aorta and pulmonary artery - Riches appear in truncus - truncal swellings, twist around one another and fuse forming aorticopulmonary septum. Conus swellings appear and fuse with interventricular septum.

Question 316

Aortic arches development

Answer 316

First arch - disappears - forms maxillary artery Second arch - disappears - stapedial and infrayhyoid arteries Third arch - common carotid and internal artery Fourth arch - left, arch of aorta and right subclavian artery Fifth arch - disappears (if formed at all) Sixth arch - pulmonary arteries All arches form and disappear multiple times in development

Question 317

Developmental cardiac defects

Answer 317

Ventricular septum defects - most common congenital defects, causes left to right shunt caused by failure of septum to fuse - three layers of membrane needs to fuse which can often go wrong. Atrial septum defect - often in conjunction with transposition of great arteries. Very common. Atria septum doesn’t fuse and great arteries carry deoxy/oxygenated blood the wrong way round. Caused by vessels spiralling incorrectly. Patent ductus arteriosus - failure of ductus arteriosus to close. Usually closes 12-14 hours after birth but if it remains open causes a right to left shunt of blood. Other artery arches can also remain there but this is most common one. Duplex aortic arch - very rare, failure of right dorsal aorta to regress. Compresses trachea And oesophagus affecting swallowing and breathing.

Question 318

Lung hilum and relations

Answer 318

Lung hilum contains the bronchi, vein and artery, veins usually inferior, bronchi posterior and have cartilage lining, arteries anterior. Lung relations - heart, lung pleura, posterior mediastinum, vagus nerve runs anterior and phrenic posterior to hilum.

Question 319

Grooves of the lung

Answer 319

Right lung - azygos, superior vena cava, oesophagus | Left lung - aorta, carotid and subclavian branches

Question 320

Pulmonary ligament

Answer 320

Runs from hilum to base of lung base

Question 321

Lung segments

Answer 321

Important for surgeries and all segments are entirely segmentally functional and so can remove one segment and have no effect on rest of lung. Right lung - superior lobe - apical, posterior and anterior segments Middle lobe - lateral and medial segments Inferior lobe - superior, anterior basal, medial basal, lateral basal, posterior basal. Left lung - superior lobe - apical and posterior segments (often forms apicoposterior segment), anterior, superior lingular, inferior lingular segments Inferior lobe - superior, anterior basal and medial basal (often form anteriomedial basal segment), lateral basal, posterior basal.

Question 322

Lymphatic drainage of lungs and visceral pleura

Answer 322

Drain into the bronchopulmonary lymph nodes at the bifurcations of the larger bronchi. From here it passes to the tracheobronchial nodes which drain into the bronchomediastinal trunk on each side. These trunks usually open directly into the junction of the internal jugular and subclavian veins. Sometimes the right duct drains into the right lymph duct and the left into the thoracic duct. The carina is the angle situated below the tracheal bifurcation. Involvement of subcarnial node with metastases from a bronchial carcinoma give the bronchoscope sign or widening the carina and of inoperability.

Question 323

Lung innervation

Answer 323

Posterior pulmonary nerve plexus lies at root of lung and compromises of sympathetic (T2-4) and parasympathetic (vagal) fibres These pass from thence around the lung root forming anterior pulmonary plexus From this plexus fibres Ito the lung along the bronchi and blood vessels Bronchial muscles receive bronchodilator fibres from sympathetic system which also weakly constricts bronchial vessels Vagus nerve supplies secretomotor fibres to pulmonary mucous glands and stretch receptors to lung passing via vagus to respiratory centre in the medulla.

Question 324

Define locomotion and gait

Answer 324

Locomotion - method of locomotion involving the use of two legs, alternatively to provide both support and propulsion. To exclude running add ‘at least one foot being in contact with the ground at all times’ Purpose of locomotion is to transport the body. Gait - describes the manner of walking rather than the process itself

Question 325

Walking conditions

Answer 325

Each limb must be able to support the body without collapse Balance must be maintained during the stance phase either statically or dynamically Swinging leg must be able to advance to position where it can take the supporting role Sufficient power must be provided to make the necessary limb and trunk movements and to advance the trunk

Question 326

Gait support in the body

Answer 326

``` Trabecular pattern of bone ensures forces are transmitted over whole surface of knee joint Menisci increase shock absorbing qualities of the knee Valves angle of femur brings knee joint into line with hip joint thus reducing width of base of support bringing it closer to centre of gravity. Mechanical axis (weight bearing line passing through hip, knee and ankle) ensures forces are equally distributed between medial and lateral condyles - thus centre of gravity need only move a short distance to bring it above the stance leg ```

Question 327

Balance and centre of gravity

Answer 327

To maintain upright stance the centre of gravity must remain directly over the area formed by the supporting feet Truncal balance and erectness must be maintained during locomotion and this is achieved by actions of the erector spinae, external and internal oblique, glut medius and minimus. Extensors of the hip and to a small extent the flexors are important in maintaining dynamic stability Eccentric contraction of plantar flexors help control and maintain balance

Question 328

Advancement and support in locomotion

Answer 328

Standing posture - the head, arm and trunk is supported by lower extremities Locomotion - these must not only be balanced over one extremity but also be transferred from one to the other. This needs coordination, balance, proprioception and the integrity of joints and muscles Study of this is gait analysis

Question 329

Gait cycle

Answer 329

The time between successive occurrences of respective movements of walking Time and distance provide basic description of gait. Stance time, single limb, double limb etc. Distance variables include stride length, step length, width of walking base etc. These factors are affected by persons age, height, sex, weight etc. Stance phase: 60% gait cycle Heel strike - initial contact. heel of leading limb strikes ground Foot flat - loading response, foot fully in contact with ground Midstance - body weight directly over supporting limb Heel off - terminal stance, heel of reference limb leaves ground Toe off - pre-swing, ipsilateral toe loses contact with ground Swing phase: 40% GC. Acceleration - initial swing, begins when toe leaves ground and continues until directly underneath body Midswing - limb passed directly beneath body Deceleration - terminal swing, when tibia passes beyond perpendicular and knee extends in preparation for heel strike

Question 330

Cadence

Answer 330

Number of steps in a given time - men usually 90-120 steps per minute and women usually 6-9 steps slower

Question 331

Position of the upper body during the gait cycle

Answer 331

Moves forwards in gait fastest during double support Trunk twists about a vertical axis with pelvis and shoulder girdle rotating in opposite directions Arms swing out of phase with legs so that as the left leg and left side of the pelvis move forwards so do the right arm and right side of shoulder girdle Total excursion of shoulder girdle is about 7° and pelvis 12° The pelvis also tips from front to back and side to side While trunk rises and falls twice in cycle - lowest in double support highest in midstance or mid swing. Total distance around 50mm Posterior fibres of deltoid and teres major are involved in backward swing and deltoid act as break in forward swing Middle fibres constantly active to prevent arm brushing against body Forward rotation takes place on side of swinging limb with opposite side acting as fulcrum. Rotation lengthens limb and reduced drop in centre of gravity

Question 332

Hip joint in gait cycle

Answer 332

Flexes and extends once during cycle Limit of flexion reached about mid swing phase and thigh is kept flexed until beginning of stance phase Peak extension reached before end of stance phase after which it begins to flex again Hip also rotates in transverse plane Internally rotates during loading response with maximum reached in midstance External rotation occurs in midswing with maximal rotation at terminal swing

Question 333

Knee joint in gait cycle

Answer 333

Flexes and extends twice in each cycle Knee is fully extended before heel contact and flexes early in stance phase Adjustment helps minimise rise in centre of gravity Extends again around midstance phase and starts flexing reaching peak in early swing phase Finally extends prior to heel contact Knee is externally rotated at initial contact and quickly changes to neutral position maintained with small fluctuations for remainder of cycle

Question 334

Ankle joint and gait cycle

Answer 334

Within few degrees of neutral position at time of heel contact and slightly inverted other foot slightly supinated by subtalar joints After heel contact it plantar flexes bringing foot flat and moving into pronation. Foot would come down too quickly in foot slap if this movement wasn’t resisted by anterior tibial muscles which contract eccentrically to lower foot gently to ground At toe off foot is everted.

Question 335

Forces involved in gait

Answer 335

External forces are inertia, gravity and ground reaction forces Inertial forces arise from inertial properties of body segments and is proportional but in opposite direction to acceleration Force of gravity acts directly downwards through centre of mass of each segment GRF represents force of ground on foot and is equal in magnitude and opposite in direction to force that body applies to floor through foot GRF probably most important force during locomotion Centre of pressure COP is point at which forces are considered to act. COP moves along set path during gait and produces pattern

Question 336

Joint moments

Answer 336

Moment is a force not having equal and opposite force directly along line of action Is a measure of tendency to cause body rotation at specific point which is different from tendency of body to move in direction of the force For moment to occur force must act on body in manner that it begins a twist and occurs when applied force doesn’t pass through centre of body Can be both internal and external to joint Internal joint moments - activated to counterbalance external moments and generated by muscles and soft tissues round a joint. An external force flexing the knee would generate internal extensor moments when the force is passed posteriorly to the knee.

Question 337

Power and locomotion

Answer 337

Energy used in locomotion assesses by measuring o2 consumption For person walking 4-5km/hour the average 100ml/kg body weight 85% energy needed is from ankle plantar flexors and 15% from hip flexors based on o2 consumption. Concentric muscle contraction results in positive work while eccentric is negative work as it decreases velocity where it acts. Two types of energy used - kinetic and potential Kinetic may be translational or rotational. Potential energy is mass x height it’s raised Amount of potential energy possessed by object is equal to kinetic energy used to raise mass. When mass stops rising kinetic energy converted to potential and back to kinetic as it falls.

Question 338

Development of locomotion

Answer 338

Most children begin to walk between 12-15 months Timing depends on neural maturation At first children walk with straight knees planting foot flat with no proper heel strike and usually with laterally rotated legs. Adults pattern rapidly establishes but base is wider and there is no arm swinging About five years old the adult walking pattern is established but stride length is shorter and cadence is higher (no of steps) No heel contact, whole leg external rotation, extended knees up to 2 years Wider base, Absence of reciprocal arm swing up to 4 years. Stride length and velocity lower and cadence higher up to 15 years old.

Question 339

Gait in the elderly

Answer 339

Gait influenced by age and pathology Tends to be increase in walking base either greater step width or greater toe angle Length of stride usually decreased as is cadence Absence of arm swing

Question 340

Stair gait

Answer 340

Ascending and descending stairs Involves swing and stance phase But initial contact is with anterior foot and travels posteriorly where body weight is accepted rather than heel strike. Weight acceptance followed by pull up phase approx 14-32% cycle in single limb support Initial pull up is unstable and whole weight shifted into stance extremity when it’s flexed at hip, knee and ankle. Task during this period is to pull weight up to next stair level. Knee extensors responsible for most energy needed. From pull up there is forward continuance period 32-64% corresponding to midstance through toe off During this period the ankle plantar flexors generate most energy More energy needed to climb stairs Descending - foot moves from plantar flexion to neutral or dorsiflexion by eccentric contraction of calf muscles. Hip and knee joints flexed by eccentric contraction of extensors. Lowering phase - heel then toes lifted followed by swing phase. Hip abductors contract in preparation for weight acceptance.

Question 341

Running gait

Answer 341

Needs greater balance and muscle strength than walking No double support phase and presence of float periods where both feet are off the ground (flight phase) and this greater balance needed. More balance control needed with more speed Muscles must generate more power both to raise the HEad, arms and trunk higher than in walking phase and balance and support them during gait cycle Muscle and joints must be able to absorb more energy generated by head arms and trunk. GRF at walking speed is between 70-120% body weight while running this can reach 250%.

Question 342

Unhappy triad

Answer 342

Medial collateral, medial meniscus and anterior cruciate usually torn all together Testing for anterior cruciate rupture - lackman test pull leg 30° for ACL stretch and pulling leg forward can displace leg if ligament is ruptured. Posterior cruciate 3x as thick as ACL and isn’t fully taught in extension so is less likely to tear Caused by medial twisting injury when limbs are extended - cruciate and collateral are taught causing a tear in the anterior cruciate, medial collateral which is attached to the medial meniscus so also gets torn Can get variations depending on valgus or Varus twisting and direction etc. Possible to tear lateral collateral and meniscus instead usually still always three components involved.

Question 343

Knee dislocations

Answer 343

Very rare due to strength and position of ligaments and muscles protecting the joint dislocations are named according to displacement of tibia Dislocations almost always have lovely rupture and injury accompanying them because they’re in the way of displacement depending on which way the tibia is displaced Classifications - dependent on tibia movement - medial, lateral, rotatory, posterior and anterior displacements.

Question 344

Traumatic knee joint injuries

Answer 344

Femur fractures - rare distally more likely the neck fractures but growth plate of femur can act as weak point even after fusion the epiphyseal line is slightly weaker Very uncommon fractures Patella fractures - 1% people have two growth plates on patella that fuse mistaken for fracture but very rare. Extensor apparatus disruption - quad tendons or patella tendon can tear Patello-femoral dislocation - tends to be laterally dislocated due to potential asymmetrical pulp asserted on patella any imbalance destabilises it to the side

Question 345

Referred knee pain from the hip

Answer 345

1/3 hip problems are referred to the knee as pain and about 5% of these have only knee pain rather than both hip and knee pain. Caused by problems at the hip affecting the obturator and femoral nerves as these travel to the knee also so can show pain there.

Question 346

Jumpers knee and Osgood Schlatters knee

Answer 346

Jumpers/patella tendinitis - tendinitis of the knee often related to Osgoods knee Osgoods - inflammatory condition affecting attachment of the patella tendon very common in sport in young people in dancing, basketball etc. With High use of quadriceps. Can also involve bone changes and spores Can happen at any age and tends to disappear with rest form strain can heal within a year or two without surgical interventions but sometimes need immobilisation

Question 347

Sinding-Larsen Johanssen Syndrome

Answer 347

Extensions of bone created in reaction to stress on the bone Have to be careful in diagnosis as in extreme cases looks like an inferior pole fracture and often misdiagnosed as fracture can also be confused with a bipartitie patella

Question 348

Bursae of knee joint

Answer 348

Suprapatellar - extends 8cm above base of patella Popliteus - between popliteus and lateral condyle of tibia Gastrocnemius - separates medial head of gastrocnemius and tibia May give rise to semimembranosus bursa These all communicate with the knee joint and if inflammation is present can disrupt the joint Anserine bursa - separates pes anserinus from tibia and is separate from knee joint Anteriorly - supra-patella, pre patella, superficial infrapatella and deep infrapatella Posteromedially - gastrocnemius, semimembranosus, pes anserine and tibial collateral ligament bursa Posterolaterally - popliteus, lateral gastrocnemius, superficial fibular collateral ligament and deep fibular collateral ligament bursa. Bakers cyst - bursitis of knee involving knee joint.

Question 349

Degenerative meniscus and tears

Answer 349

History - pain, medial 20x more common than lateral due to immobility. Often follows trauma Physical exam - joint line tenderness and pain with full flexion Tear types - complete longitudinal, bucket handle, displaced bucket handle, parrot beak, flap, displaced flap, radial, double flap and incomplete longitudinal. Arthroscopy good for diagnosis and treatment. Basis of surgery - conserve tissue, remove abnormal tissue and prevent further tear, repairing where possible.

Question 350

Osteochondritis dissecans

Answer 350

Joint disorder in which cracks form in the articular cartilage and the underlying subchrondral bone Usually causes pain and swelling of affected area which catches and locks during movement

Question 351

Charcots knee

Answer 351

Joint or neuropathic arthropathy resulting in significant joint destruction and instability Rare but very challenging for surgery Still lots unknown

Question 352

Paget’s disease

Answer 352

Bone interferes with body’s normal recycling process where new bone tissue gradually replaces old Overtime can cause bones to become fragile and misshapen Most commonly occurs in the pelvis, skull, spine and legs

Question 353

Auricles

Answer 353

One left one right attached to either atria in the anterior surfaces Wrinkled pouch structures Purpose is to increase capacity of atrium and increase volume of blood it can contain. They also release atrial natriuretic peptide mostly produced in the left auricle which stimulates Na secretion in response to too high blood volumes

Question 354

Heart chambers significant features

Answer 354

Crista terminalis - smooth muscular ridge on roof of atrium in front of the SVC to the IVC in the right atria Septonarginal trabecula - forms bridge begween IVS and base of anterior papillary muscle. Carries the right bundle of antrioventricular bundle to anterior right ventricle wall Conus arteriosus - smooth walls of right ventricle derived from embryonic Bulbus cordis

Question 355

Pericardium

Answer 355

Protective sac around the heart attached to the sternum via the anterior mediastinum, the diaphragm and posterior mediastinum, ascending aorta, pulmonary trunk, SVC and superior mediastinum. Consists of outer fibrous layer and two internal serous layers (parietal and visceral) Keeps heart fixed in place, prevents overstretching too much and overfilling with blood, lubricates heart to prevent friction with tissues around it as it beats and protects heart from infections from nearby organs. Pericardiophrenic ligaments - strong adhesions where floor of fibrous pericardium is firmly attached with central tendon of diaphragm. Sternopericardial ligaments - weak adhesions variably present connecting anterior fibrous pericardium to posterior surface of upper and lower sternum. Oblique pericardial sinus - blind ending cul de sac behind the heart opening into the pericardial space proper inferiorly. IVC to be right, inferiorly the pulmonary vein and right superior pulmonary vein. To the left is left pulmonary vein and left superior pulmonary vein. Transverse pericardial sinus - superior to left atrium and posterior to intrapericardial parts of pulmonary trunk and ascending aorta and anterior to the SVC on the right and left atrial appendage on left. Clinical significance during cardiac surgery allows surgeon to isolate pulmonary trunk and ascending aorta and apply temporary ligature or clamp. Blood supply and innervation - phrenic nerve give somatic fibres common source of referred pain. Pericardiophrenic phrenic, musculophrenic and inferior phrenic arteries branched from internal thoracic artery. Veins drain into brachiocephalic vein or SVC.

Question 356

Pericardial problems

Answer 356

Pericardial effusion - buildup of too much fluid between pericardium and heart, possible causes include inflammatory conditions like lupus or RA, underactive thyroid, infections etc. Pericarditis - swelling of pericardium caused by infections, bacteria, autoimmune disorders, heart attack etc. Cardiac tamponade - caused by buildup of fluid, blood or gas or tumour in your pericardial cavity. Places pressure on heart which prevents it filing and emptying effectively. Can be a complication of effusion. Sign of presence is large drop in blood pressure and is life threatening if not treated fast.

Question 357

Coronary artery dominance

Answer 357

The posterior interventricular branch usually branches from the right coronary artery, meaning the heart is right dominant. This is more favourable as the vessel travels lesser distance to reach the SAN in the right atria so is less likely to be damaged and lose blood supply to the SAN. Some people can be left dominant when their posterior interventricular branch stems from the left coronary artery increasing their risk of SAN ischaemia

Question 358

Heart innervation

Answer 358

Vagal and sympathetic fibres Right vagus primarily innervated SAN while the left innervates the AVN. Can be significant overlap and anatomical distribution changes

Question 359

Koch’s triangle

Answer 359

Anatomical area located in the superficial paraseptal endocardium of right atrium Boundaries are coronary sinus orifice, tendon of Tadaro, septal leaflet of right AV valve.

Question 360

Bachman’s bundle

Answer 360

Branch of the anterior internodal tract that resides on inner wall of left atrium Functions as a conducting connection between the right and left atria to enable contraction as all other atria tissue is non conducting

Question 361

Cardiac fibrous skeleton

Answer 361

High density single structure of connective tissue forms and anchors the valves and influences forces exerted through them Cardiac skeleton separates and partitions the atria from the ventricles Collagen fibres encircle bases of major heart vessels providing structure and support to heart. Ageing can cause Ca accumulation and stiffening contributing to delayed depolarisation waves from the AVN to bundle of His. Function is to ensure electrical and autonomic energy generated is conducted and cannot return. Does this by establishing electrically impermeable boundary within the heart. Dense connective tissue is non conductive forcing electrical activity in particular pathway of conduction.

Question 362

Peroneus tertius

Answer 362

Arises from lower third of anterior surface of fibula from lower part of interosseous membrane and intermuscular septum and peroneus brevis muscle Passes under superior extensor retinaculum of foot and inferior extensor retinaculum of foot in same canal as extensor digitorum longus Inserts into dorsal surface of base of metatarsal bone of fifth digit. Innervated by deep fibular nerve Weak dorsi flexor and everts the foot. May be absent in humans often.

Question 363

Knee joint anatomy

Answer 363

Capsule - deficient anteriorly Synovium and bursa Ligaments: collaterals, cruciate, meniscofemoral, oblique popliteal, arcuate Nerve supply femoral, obturator, common fibular and tibial Blood supply genicular arteries

Question 364

Patello-femoral joint

Answer 364

Articulating surfaces of posterior patella and femur is highly susceptible to injury such as: Arthritis Patellofemoral pain syndrome: repeated contact of joint surfaces leading to irritation and inflammation, pain and limited motion at knee Chondromalacia: irritation of joint may lead to breakdown of cartilage. In chronic form May need surgical repair. Common in runners, footballers, skiers and cyclists.

Question 365

Q angle

Answer 365

Angle between the quadriceps tendon and patella tendon in full extension Increases in: increased femoral anteversion, external tibial torsion, laterally positioned tibial tuberosity and tight lateral retinaculum Females have wider hips and therefore wider Q angle 17° vs males 14° average

Question 366

Meniscofemoral ligaments

Answer 366

Humphrey’s ligament - anterior meniscofemoral is less than 1/3 diameter of posterior cruciate ligament Arises form posterior horn of lateral meniscus and inserts at distal edge of femoral PCL attachment. Runs anterior to PCL Wrisbergs ligament - posterior meniscofemoral usually larger than ligament of Humphrey up to 1/2 diameter of PCL and extends from posterior horn of lateral meniscus to medial femoral condyle

Question 367

Arcuate popliteal ligament

Answer 367

Extracapsular ligament of knee Y shaped and attached to posterior portion of head of fibula Two insertions into popliteus media medically blending with oblique popliteal ligament and laterally onto lateral epicondyle of femur blending with lateral head of gastrocnemius muscle

Question 368

Middle genicular artery

Answer 368

Arises in the knee joint a small branch of the popliteal artery piercing the oblique popliteal ligament and supplying the ligaments and synovial membrane in the interior of the articulation

Question 369

Popliteal fossa

Answer 369

Boarders - Superomedial, semimembranosus Superolateral, biceps femoris Inferomedial, medial Hess of gastrocnemius Inferolateral, lateral head of gastrocnemius and plantaris Contains the popliteal artery, vein, tibial nerve and common fibular nerve, small saphenous vein pierced popliteal fascia entering fossa Swelling in fossa May indicate bakers cyst - inflammation of semimembranosus bursa usually in conjunction with arthritis can rupture and produce symptoms similar to DVT but usually self resolves Popliteal aneurysm - dilation of artery greater than 50% normal diameter. Popliteal fascia is non extensible so aneurysm compresses other structures in fossa causing pain eg tibial nerve compression very common. Weakens plantar flexion.

Question 370

Gait pathology

Answer 370

Reasons for pathological gait: Pathology or injury to specific joint Compensating for injury on the same side Compensating for injury on opposite side In painful gait can be result of injury to the hip, knee, ankle or foot changing the timing of swing and stance phases Stance phase on injured side is shorter then non injured and swing phase on injured side is longer Result is weight is transferred as quickly as possible to non injured side making step length shorter and decreasing walking velocity and cadence. Most common causes of gait variation - lateral trunk bending, abnormal hip rotation, functional leg discrepancy, insufficient push off.

Question 371

Lateral trunk bending and gait variation

Answer 371

Adopted for- painful hip, weak hip abductors, abnormal hip joint such as congenital dislocation, coxa vara or slipped femoral epiphysis. Is observed in frontal plane During double support trunk is upright but swings side to side in swing phase leaning toward stance leg. Bending may be unilateral or bilateral which produces waddling gait Usually associated with painful hip like arthritis to reduce the force on the joint. Weak abductors means pelvis can’t be stabilises in single leg stance and pelvis may dip on unsupported side may occur in standing as well as walking reducing force acting on muscles reducing dip in pelvis. This is called trendelenburgs sign. Abnormal hip joints may be due to dislocations etc. In all cases gluteus medius muscle length is reduced because greater trochanter moves proximally toward pelvis brim. Result is contraction of glut med with reduced tension. To compensate the subject trunk bends to supporting hip.

Question 372

Coxa vara

Answer 372

Normal femoral neck shaft angle is 160° at birth and decrease to 125 in adults Coxa vara is rare disorder in early infancy due to defect in endochondral ossification in medial femoral neck As child become more mobile crawling and standing the femoral neck bends or fractures shortening the leg and bowing angle Can develop at any age if femoral neck gives way eg rickets Hip is stabilises by muscles parallel to femoral neck keeping it in line with acetabulum and forces of muscles (piriformis, obturator internus And gluteus medius and minimus) result in adaptation of joint Longitudinal muscles tend to dislocate joint so hip is stabilised in abduction and immobilisation in position can be used as treatment

Question 373

Abnormal hip rotation

Answer 373

One of three causes: problem with muscles, fault in foot contacting ground or compensatory movement Usually result of muscle imbalance between hip rotators Lateral rotators - piriformis, obturator internus And externus, quadratic femoris, pectineus, glut med and max. Medial rotators - tensor fascia Lata, glut med, glut min, obturator externus. When medial rotation is at 30-40° obturator externus And pectineus no longer act as Lateral rotators instead as medial. Glut med and min still medial rotators but once beyond 40° gluts and TFL become lateral rotators also. Direction of muscle fibres dictates action. Many foot disorders produce abnormal hip rotator most noticeably of foot is everted or inverted. May be result of weakness of fibular and tibial muscles. External rotation mag also be result of quadriceps weakness.

Question 374

Functional leg discrepancy

Answer 374

To overcome problem of anatomical differences in leg length several closely related strategies used- circumduction, hip hiking, steppage, vaulting. In normal gait cycle stance leg needs to be longer than swing if not leg will hit the ground To extend the leg the hip is extended as is the knee and ankle is plantar flexed. Swinging limb is shortened. Abnormalities I’m functional leg length can be due to neurological or musculoskeletal problems Circumduction - leg is swung outward. Can also be used to advance swing if hip flexors are weak Hip hiking - pelvis lifted on swing side by trunk muscles. May be used when hamstrings are weak and knee extended prematurely making limb too long towards end of swing phase. Steppage - during swing there’s an exaggerated knee and hip flexion lifting foot higher than usual to clear ground. Most common strategy in foot drop cases Vaulting - increases stance leg clearance by going on toes

Question 375

Insufficient push off gait

Answer 375

Push off normally responsible for major portion of work in walking Energy produced by the soleus in late stance phase delivered to trunk to accelerate forward in conjunction with rectum femoris and gastrocnemius If other parts of the foot are used this reduces power and walking efficiency and step length. If weight remains on heel there’s lift off where whole foot is lifted off the ground Foot deformities and muscle weakness may result in insufficient push off

Question 376

Mediastinum

Answer 376

Central compartment of thoracic cavity located between the pleura containing most thoracic organs Acts as a conduit for structures passing through thorax. Divided into superior and inferior mediastinum at the sternal angle at the level of L4/5. Superior mediastinum - starts at superior thoracic aperture to the sternal angle, sides of pleura. Inferior mediastinum - extends down from sternal angle to the diaphragm. Further subdivided into the anterior, middle and posterior mediastinum.

Question 377

Superior mediastinum contents

Answer 377

Arch of aorta and three major branches - brachiocephalic supplying right side of head and neck and right upper limb, left common carotid supplying left side of head and neck, and left subclavian supplying left upper limb. Superior vena cava - brachiocephalic veins draining upper body, left superior intercostal vein collecting left 2nd and 3rd intercostal veins and draining into brachiocephalic vein. Azygos vein receiving blood from right posterior intercostal veins. Left intercostal veins drain into hemiazygos and accessory hemiazygos veins before joining azygos vein around T7-9. Right vagus nerve running parallel to trachea passing posterior to SVC and right pulmonary bronchus. Left vagus nerve - enters superior mediastinum between left common carotid and left subclavian arteries. Descends anteriorly to aortic arch before going posterior to left bronchus. Left recurrent laryngeal nerve arising from left vagus passes under aortic arch to the left of ligamentum arteriosum. Phrenic nerve - roots c3-5 enters lateral to great vessels. Cardiac nerves - from superior, middle and inferior cardiac ganglion forming superficial and deep cardiac plexuses. Superior sits between aortic arch and right pulmonary vein. Deep plexus on the surface of the trachea at bifurcation at T4. Sympathetic trunk - runs bilaterally to vertebral bodies along length of vertebral column. Thymus - in children but remnants in adults may be present. Trachea - bifurcates at T4 into primary bronchi Oesophagus - ascends towards pharynx joins it at level of T6 Thoracic duct - passes to left of oesophagus on path to junction of left internal jugular and subclavian veins. Muscles - sternohyoid and sternothyroid muscles from posterior surfaces of manubrum. Part of infrahyoid muscle group of neck.

Question 378

Anterior mediastinum contents

Answer 378

Boarders - mediastinal pleura laterally, anteriorly body of sternum and transversus thoracis muscles, posteriorly pericardium, roof is continuous with superior mediastinum at sternal angle, floor is diaphragm. Contents - sternopericardial ligaments, tethering pericardium to sternum, fat, lymphatic vessels, lymph nodes and branches of internal thoracic vessels. Thymus unless receded.

Question 379

Middle mediastinum contents

Answer 379

Boarders - pericardium anteriorly, posteriorly, mediastinum laterally, sternal angle superiorly, inferiorly the diaphragm. Contents - heart and great vessels, pericardium and tracheal bifurcation and main bronchi. Vessels - ascending aorta, pulmonary trunk and SVC. Nerves - cardiac plexus, located at base of heart contains sympathetic T1-4 and parasympathetic fibres from vagus nerve. Divided into superficial and deep. Vagus nerve travels posterior to hilum and exits at T10 via oesophageal hiatus in diaphragm. Phrenic nerves left and right - provide motor innervation to diaphragm arise in neck and descend through middle mediastinum reaching diaphragm. Lymphatic - tracheobronchial lymph nodes associated with trachea and bronchi. Characteristically enlarges in lung pathologies. Form from gathering of bronchial nodes within hilum of lungs. Individual nodes are connect via fine lymphatic channels

Question 380

Posterior mediastinum contents

Answer 380

Boarders - laterally pleura, pericardium anteriorly, T5-12 posteriorly, sternal angle roof and diaphragm floor. Thoracic aorta - begins at T4 descends to the left of vertebrae becoming more medial as it descends. Passes through aortic hiatus at T8. Branches - posterior intercostal arteries, nine pairs supplying intercostal spaces apart from first two. Pass parallel to ribs. Bronchial arteries - paired visceral usually one or two. Left bronchial arteries arise directly from thoracic arteries. Those on the right branch indirectly from right posterior intercostal arteries. Supply tracheobronchial tree. Oesophageal arteries - unpaired visceral branches. Arise from anterior aorta. Most individuals have two but can be up to five. Supply oesophagus. Superior phrenic arteries - arise from anterior thoracic aorta at aortic hiatus varying in number supply diaphragm. Oesophagus - connects pharynx to stomach, posterior to arch of aorta and heart. Initially on the right then moves left as it descends. Exits via oesophageal hiatus at T10. Oesophageal plexus - nerve network around oesophagus compromising of left and right vagus nerves. Above the diaphragm the fibres converge forming anterior vagal trunk and posterior vagal trunk which travel along surface of oesophagus as it exits the thorax. Thoracic duct - largest lymphatic vessel in body returning most lymphatics into venous system (all but the right superior quadrant). Originates from cisterna chyli in abdomen and enters mediastinum through aortic hiatus. Ascends to lie directly anterior to T6-12 before going to the left as it goes into the superior mediastinum. Receives lymph drainage from intercostal spaces and other spaces throughout number of branches. Azygos vein system - drains body walls and mediastinal viscera emptying into SVC consists of three major veins: azygos formed of union of right lumbar vein and right subcostal vein. Enters mediastinum via aortic hiatus and drains into SVC. Hemiazygos formed of union of left lumbar vein and left subcostal vein. Enters mediastinum through left crus ascending on left side at level of T8 turns to right and combines with azygos. Accessory hemiazygos vein formed by union of fourth to 8th intercostal veins. Drains into azygos at T7. Sympathetic trunks - paired bundles of nerves extend from base of skull to coccyx. Thoracic region these bundles are called thoracic sympathetic trunks. Lower splanchnic nerves - arising from sympathetic trunks and continue inferiorly supplying viscera of abdomen.

Question 381

Oesophagus

Answer 381

connects pharynx to stomach, posterior to arch of aorta and heart. Initially on the right then moves left as it descends. Exits via oesophageal hiatus at T10. Oesophageal plexus - nerve network around oesophagus compromising of left and right vagus nerves. Above the diaphragm the fibres converge forming anterior vagal trunk and posterior vagal trunk which travel along surface of oesophagus as it exits the thorax. Fibres from cervical and thoracic sympathetic trunks. Fibromuscular tube 25cm long. Begins in neck at C6 level and continues superiorly with laryngeal part of pharynx Muscular layers - superior third is voluntary striated muscle, middle third is voluntary striated and smooth muscle and inferior third is smooth muscle. Sphincters - two present known as upper and lower Upper - anatomical striated muscle sphincter at junction between pharynx and oesophagus. Produced by cricopharyngeus muscle. Normally is constructed to prevent entrance into oesophagus. Lower - physiological sphincter located in gastro oesophageal junction to the left of T11 marked by change from oesophageal to gastric mucosa. Formed of four phenomena: oesophagus enters stomach at acute angle. Walls of intra-abdominal section of oesophagus are compressed when there’s positive intra abdominal pressure. Folds of mucosa aid in occluding lumen at junction. Right crus of diaphragm has pinch cock effect. Vasculature - thoracic part receives branches from thoracic aorta and inferior thyroid artery (branch of thyrocervical trunk) venous drainage into systemic occurs via branches of azygos veins and of inferior thyroid vein. Abdominal part supplied by left gastric artery (branch of coeliac trunk) and left inferior phrenic artery. Part of oesophagus has mixed venous drainage via two routes: to portal circulation via left gastric vein or to systemic circulation via azygos vein. These form the porto-systemic anastomoses, connection between portal and systemic venous systems. Lymphatic drainage - superior third by cervical lymph nodes, middle third by superior and posterior mediastinal nodes and lower third by left gastric and celiac nodes. Disorders - Barrett’s oesophagus, metaplasia of power squamous epithelium to gastric columnar type. Caused by chronic acid exposure as result of malfunctioning lower oesophageal sphincter. Acid irritates epithelium leading to metaplastic change. Causes burning indegestion sensation.

Question 382

Thoracic duct

Answer 382

Thoracic duct - largest lymphatic vessel in body returning most lymphatics into venous system (all but the right superior quadrant). Originates from cisterna chyli (lumbar lymph ducts at L2) in abdomen and enters mediastinum through aortic hiatus. Ascends to lie directly anterior to T6-12 before going to the left as it goes into the superior mediastinum. Receives lymph drainage from intercostal spaces and other spaces throughout number of branches. Numerous valves present. Receives branches from middle and superior intercostal spaces both sides via collecting trunks. Also receives input from posterior mediastinal branches. Empties into union of internal jugular and subclavian veins and may open into left subclavian veins

Question 383

Azygos vein system

Answer 383

vein system - drains body walls and mediastinal viscera emptying into SVC consists of three major veins: azygos formed of union of right lumbar vein and right subcostal vein. Enters mediastinum via aortic hiatus and drains into SVC. Hemiazygos formed of union of left lumbar vein and left subcostal vein. Enters mediastinum through left crus ascending on left side at level of T8 turns to right and combines with azygos. Accessory hemiazygos vein formed by union of fourth to 8th intercostal veins. Drains into azygos at T7.

Question 384

Ankle sprains

Answer 384

Lateral - most common 95% ankle sprains, lateral ligaments may be torn: ATFL 65-75%, ATFL and CF 25%, ATFL, CF and PTFL hardly ever all three

Question 385

Ankle sprains, fractures and dislocations

Answer 385

Ligament ruptures Malleolar fractures/ ankle fractures or fracture dislocations Fractures of talus and calcaneus Fractures of midfoot, Lisfrancs fracture and dislocation Fracture of forefoot/metatarsals (Jones fracture of base of MT1) Syndesmosis injury with distal fibula fracture

Question 386

Jones fractures

Answer 386

Caused by: Inversion and plantar flexion, Direct force, repetitive trauma, most, Common fracture site is base of fifth metatarsal Signs and symptoms: Immediate swelling, pain over fifth metatarsal, high nonunion rate, course of healing is unpredictable Management: Controversial treatment, crutches with no immobilisation, gradual progression to weight bearing as pain subsides. If nonunion or fracture is evident, surgery with internal fixation may be required

Question 387

Ankle anterior compartment syndrome

Answer 387

Increased pressure in muscles decreases blood flow, and nerve supply Can be acute or chronic Acute - medical emergency, usually caused by severe injury. Without treatment can lead to permanent muscle damage Chronic - aka exertional compartment syndrome usually not medical emergency often caused by athletic exertion.

Question 388

Tarsal tunnel syndrome

Answer 388

Compression of tibial nerves as it travels trough the tarsal tunnel along inner leg behind medial malleus Tibial nerve gets entrapped bear medial malleolus deep to flexor retinaculum Causes plantar tingling or burning as opposed to local pain with tibialis posterior tendinitis Doesn’t involve the whole foot as with diabetes Tinel test - can lose plantar sensation or may elicit toe clawing Needs arch support if over pronated and need to consider nerve conduction velocity tests

Question 389

Posterior tibial tendon insufficiency

Answer 389

Unilateral flat foot Usually a degenerative condition of the tendon Most missed problem of the foot Pain and aching between the navicular and medial malleolus also looks swollen Treatment arch supports, NSAIDS, PT. May need surgery

Question 390

Talipes equinovarus - club foot

Answer 390

Congenital deformity of the foot with unknown cause Treated using Ponseti method - gentle manipulations and series of plaster casts gradually improving the positioning of the foot. Small surgery sometimes needed called Achilles tenotomy involving releasing Achilles’ tendon allowing the heel to fully drop down If too severe can need more surgery

Question 391

Pes planus - flat foot

Answer 391

Caused by excessive probation and forefoot varus, wearing tight shoes, being overweight, excessive exercise placing undo stress on foot arch Signs and symptoms - pain, weakness or fatigue in medial longitudinal arch Calcaneus eversion Bulging navicular Flattening of medial longitudinal arch Dorsi flexion with lateral splaying of 1st metatarsal Management - orthotics with medial wedge may be used Taping of arch can also be used for additional support

Question 392

Pes cavus - High arch

Answer 392

``` Caused by: Excessive supination Associated with forefoot valgus Accentuated high medial longitudinal arch Signs and symptoms: Poor shock absorption Metatarsalgia / foot pain Clawed or hammer toes Shortening of plantar fascia Heavy callus development on ball and heel of foot Management - orthotics with lateral wedge may be used Stretch plantar fascia ```

Question 393

Hallux valgus

Answer 393

Caused by exocytosis of first metatarsal head associated with: Forefoot varus, wearing ill fitting shoes and wearing shoes with pointed toes Bursa becomes inflamed and thickens - enlarges the joint and causes lateral malalignment of the great toe - bunionette (Tailors bunion) impacts fifth metatarsalphalangeal joint causes medial displacement of fifth toe Signs and symptoms: initial tenderness, swelling, enlargement of joint. As inflammation continues angulation of joint increases and pain increases Tendinitis in great toe flexors may develop Management - wear correct fitting shoes, orthotics may be used. Padding over first metatarsal head with tape splint between 1/2 my toe may be used Bunioectomy May be necessary

Question 394

Hammer, mallet and claw toes

Answer 394

Hammer toe: flexion contracture of PIP joint which can be fixed Mallet toe: flexion contracture of DIP joint Claw toe: flexion contracture of DIP with hyperextension at MIP joint usually seen in diabetes Signs and symptoms : swelling, pain, callus formation, occasionally infection