MSK sessions 1-4 Flashcards
(297 cards)
1
Q
When do the limb buds appear?
A
Towards the end of the fourth week of development
2
Q
Do both limb buds appear at the same time?
A
The development of the upper limb precedes that of the lower limb by a few days.
Embryo development from cranial to caudal end.
3
Q
What makes up the limb bud?
A
A mass of proliferating mesenchyme covered by a layer of ectoderm
Apical ectodermal ridge- formed by division of ectodermal cells at apex of the bud
4
Q
How do limb buds elongate?
A
The AER is thought to exert an inductive influence on the limb mesenchyme that promotes proliferation
5
Q
What controls axial specification when the limb is developing?
A
Proximal-distal axis = apical ectodermal ridge (AER)
Dorsal-ventral axis = ectoderm
Anterior- posterior axis = zone of polarising activity (ZPA)
6
Q
How does the AER cause proximal to distal growth?
A
AER signals to stimulate affect only localised mesenchyme
AER signals inhibit differentiation of mesenchyme
Proximal mesenchyme is now far away and not under the influence of AER
Proximal mesenchyme begins to differentiate into constituent tissues
Panels appear in distal most part of limb bud.
AER induces the development of digits within the hand/foot places
7
Q
What maintains the AER?
A
ZPA
8
Q
What are the functions of ZPA?
A
Generation of asymmetry in the limbs (between pinky and thumb)
Maintains the AER
9
Q
Where is the ZPA found?
A
Posterior base of the limb bud
10
Q
How do the digits form?
A
AER is maintained only over the tips of the digital rays
Apoptosis occurs between them
Digital rays develop into cartilaginous models
11
Q
What is syndactyly?
A
Fusion of digits- may involve CT or bones may fuse
12
Q
What is polydactyly?
A
Extra digits
13
Q
What is amelia?
A
Complete absence of a limb
14
Q
What is meromelia?
A
Partial absence of one or more limb structures
15
Q
What is phocomelia?
A
Hand or feet are connected directly to the trunk
16
Q
What is usually the cause of malformation resulting in abnormalities of the limb?
A
Genetics
Inherited mutation or spontaneous mutation of a gene coding for a protein involved in coordination of an event
17
Q
What is constriction banding and how does it cause abnormalities in the limbs?
A
Normal limbs are formed.
Strands of amniotic membrane fall off and encircle the limb, constricting it and causing truncation.
18
Q
Can truncation of the limbs due to constriction banding be genetically inherited?
A
NO
Normal limbs form- obstruction has affected a normal pathway
19
Q
How did thalidomide cause abnormalities in the limbs?
A
Teratogenic agent which disrupts AER so stops elongation of limb buds
20
Q
What initiates compartmentalisation of the limb buds?
A
Mesenchyme loses the signal from AER to stay undifferentiated.
21
Q
Describe compartmentalisation of limb buds?
A
- Cartilaginous models of skeletal stem appears creating a dorsal and ventral compartment.
- Myogenic precursors migrate into limbs from somites and sit either dorsally or ventrally. Ventral = flexor. Dorsal = extensor
- Individual muscles split from muscle masses
- Somites develop either side of the neural tube and each somite develops its own spinal nerve. The spinal nerve will innervate derivatives of this somite
22
Q
Describe rotation of the limbs
A
Upper limbs laterally
Lower limbs medially
23
Q
What are the six motions of the hand?
A
Grip Hook Spherical grip Tip to tip Palmar Lateral
24
Q
Describe the composition of the brachial plexus.
A
Roots Trunks Divisions Cords Branches
25
What are the trunks of the brachial plexus?
Upper trunk = c5 and c6
Middle trunk = c7
Lower trunk = c8 and t1
26
Describe the divisions of the brachial plexus
Each trunk splits into anterior and posterior divisions.
Anterior divisions- go on to supply the anterior compartments of the upper limb
Posterior divisions- go on to supply the posterior compartments of the upper limb
27
Describe the cords of the brachial plexus.
This is relative to the axillary artery
Lateral cord
Anterior division of the superior trunk
Anterior division of the middle trunk
Posterior cord
Posterior division of the superior trunk
Posterior division of the middle trunk
Posterior division of the inferior trunk
Medial cord
Anterior division of the inferior trunk
28
Describe the anatomical boundaries of the axilla.
Lateral wall
Intertubercular groove of the humerus
Medial wall
Serratus anterior and thoracic wall
Anterior wall
Pectoralis major and underlying pectoralis minor and subclavius
Posterior wall
Subscapularis, teres major, latissimus dorsi
Apex
Lateral border of first rib
Superior border of scapula
Posterior border of clavicle
29
Describe the contents of the axilla
Axillary artery and its branches
Axillary vein and its tributaries
Infraclavicular part of the brachial plexus
Five groups of axillary lymph nodes and associated lymphatics
Long thoracic and intercostobrachial branches
Axillary fat and areolar tissue
30
What is thoracic outlet syndrome?
The apex of the axilla is an opening between the clavicle, the first rib and the scapula
In the apex, vessels and nerves may become compressed
Presentation:
Pain in limb, tingling, muscle weakness and discolouration
- where depends on what nerve is affected
31
What is a lymph node biopsy used for?
Diagnosis of breast cancer
| 65% of lymph from breast drains into axillary lymph nodes
32
Axillary lymph nodes may need to be removed to prevent cancer spreading in axillary clearance. What structure is at risk of damage in this process and what are the consequences?
Long thoracic nerve
| Winged scapula
33
What is the quadrangular space?
Gap in posterior wall of the axilla which allows access to the posterior arm and shoulder area.
```
Bounded by:
Subscapularis and capsule of shoulder joint superiorly
Teres major inferiorly
Long head of triceps medially
Surgical neck of humerus laterally
```
Structures passing through:
Axillary nerve
Posterior circumflex humeral artery
34
What is the clavipectoral triangle?
Opening in anterior wall of axilla
Bounded by:
Pectoralis major
Deltoid
Clavicle
Structures passing through:
Cephalic vein
Medial pectoral nerve
Lateral pectoral nerve
35
What are the two passageways exiting the axilla?
Quadrangular space
| Clavipectoral triangle
36
What are the contents of the fibrous axillary sheath?
Axillary artery
Axillary vein
Cords and branches of the brachial plexus
37
For the purpose of anatomical description, the axillary artery is divided into three sections. What are the anatomical landmarks that define these three sections?
First part- begins at lateral border of first rib as a continuation of the subclavian artery
Second part- posterior to pectoralis minor
Third part- lateral to pectoralis minor and continues as the brachial artery at the inferior border of teres major
38
Explain what happens if the AER is disrupted and give one mechanism causing its disruption.
Shortened limbs/no limb growth
| Mechanism: Interference affecting blood vessels of AER
39
What is the structural defect underlying congenital dislocation of the hip (CHD)?
Underdevelopment of acetabulum and head of femur.
40
CHD is associated with breech presentation (i.e. the buttocks of the fetus are inferior and would be delivered first, rather than the head). Speculate on why this might be so.
Breech presentation may place undue pressure on the developing hip joint: fails to complete normal development.
41
For the purpose of anatomical description, the axillary artery is divided into three sections. What are the anatomical landmarks that define these three sections?
The first part of the axillary artery begins at the lateral border of the first rib as a continuation of the subclavian artery.
The second part of the axillary artery lies posterior to pectoralis minor.
The third part lies lateral to pectoralis minor and continues as the brachial artery at the inferior border of teres major.
42
What is the difference between palmar abduction and radial abduction of the hand?
Palmar abduction- occurs in sagittal plane
Radial abduction- continuation of extension in coronal plane
43
What is the most common arrangement of fascicles?
Parallel - fibres run parallel to force generating axis
44
How are the fibres organised in the biceps brachial muscle?
Parallel-fusiform
Wide and cylindrically shaped in the centre
Taper off at the ends
45
How are the fascicles arranged in the deltoid muscle?
Multipennate
46
What is the difference between an origin and insertion in terms of stability?
Origin = proximal, greater mass, more stable during contraction
Insertion = distal, moved by contraction
47
What is compartment syndrome?
Trauma in one compartment can cause internal bleeding which exerts pressure on blood vessels and nerves.
When there is a fracture, there is bleeding into a compartment of the forearm which is enclosed by fascia.
Pressure increases and veins have distensible walls so these collapse
As pressure increased further, blood supply to this compartment is cut off.
This results in ischaemia and necrosis of the muscles in this compartment
48
How does compartment syndrome present?
Deep constant poorly localised pain
Aggravated by passive stretch of a muscle group
Parasthesia
Compartment may feel tense
Swollen shiny skin, sometimes with obvious bruising
Prolonged capillary refill time
EARLY
Pain our of proportion to the injury
Pain with passive movement
```
LATER
Paralysis
Pulselessness
Parasthesia
Pallor
Poikilothermia (perishing cold)
```
49
How is compartment syndrome treated?
Fasciotomy - incision of overlying fascia or a septum to relieve pressure in the compartment concerned
50
What is the difference between neutralisers and fixations?
Neutralisers prevent unwanted actions of a muscle
| Fixators stablise a joint
51
What are the two types of isotonic contraction?
1. Concentric contraction
Muscle shortens
2. Eccentric contraction
Refers to active contraction of muscles whilst they are lengthening
52
Which type of isotonic contraction is damaging to muscles and results in delayed onset of pain?
Eccentric contraction = pain is not felt for about 8 hours and is maximal 1 or 2 days later
53
What is titin?
Protein that connects the Z line to the M line in the sarcomere.
Limits the range of motion of the sarcomere in tension, contributing to the passive stiffness of muscle.
54
What is the most common lever found in the body?
```
Third class lever
Effort is between load and fulcrum
```
55
What is malignant hyperthermia and what is it triggered by?
Triggered by volatile anaesthetic agents and succinylcholine in susceptible individuals
Leads to uncontrolled increase in oxidative metabolism and an increase in body temperature
56
What is the most common genetic cause of malignant hyperthermia?
Polymorphism in the ryanodine receptor
Receptor activated by volatile anaesthetic agents
Massive increase in intracellular calcium from intracellular stores
High activity of SERCA pump which consumes ATP
Excessive heat production
57
What is myotonia congenita?
Cause:
mutations in chloride channel
Recessive or dominant
Symptoms:
muscle stiffness, particularly in leg muscles, enhanced by cold and inactivity, relieved by exercise
Treatment:
None, symptoms received with anticonvulsant drugs
58
What is rigor mortis?
ATP depleted
| Myosin heads cannot detach
59
What is tetany?
Consecutive action potentials result in summation giving a slightly larger force with each contraction.
Eventually a limit is reached where no further force can be produced and this is tetany.
60
What is tetanus?
Muscles contract continuously due to bacterial infection and release of tetanus toxin which prevents the neuromuscular synapse from relaxing
61
What is hypotonia?
Lack of skeletal muscle tone
(All muscle has some degree of baseline tone due to the elasticity of the muscle tissue and low levels of motor neurone activity)
62
What are the causes of hypotonia?
Damage to the motor cortex or cerebellum or spinal cord
| Degeneration of muscle itself (myopathy)
63
Which physiological process, occurring within the muscle fibre, causes skeletal muscle relaxation?
Active transport of Ca2+ ions from cytosol back into SR
64
What is the shoulder girdle?
Clavicle and scapula
65
Name the joints present at the shoulder girdle.
Sternoclavicular joint
Acromioclavicular joint
Scapulothoracic joint
Glenohumeral joint
66
What is the glenoid labrum?
Fibrocartilage rim that deepens the glenoid fossa to reduce the disproportion in surfaces and increase stability
67
Describe what the joint capsule of the shoulder is and where it is.
Fibrous sheath which encloses structures of the joint.
| Extends from the anatomical neck of the humerus to the border of the glenoid fossa
68
What are the main clinically relevant bursae of the shoulder joint?
Subacromial bursa
Inferior to deltoid and acromion
Superior to supraspinatus and joint capsule
Inflammation of this bursa is the cause of many shoulder problems
Subscapularis bursa
Between subscapularis tendon and scapula
Reduces wear and tear on tendon during movement of the shoulder joint
69
What are the intracapsular ligaments of the shoulder joint?
Superior, middle and inferior glenohumeral ligaments Thickenings of the joint capsule
Between glenoid fossa and anatomical neck of the humerus
Stabilise anterior aspect of the joint
70
What are the extracapsular ligaments of the shoulder joint? (4)
Coracohumeral ligament
Between coracoid process and humerus
Coracoacromial ligament
Between acromion and coracoid process
Coracoclavicular joint
Between clavicle and coracoid process
Transverse humeral ligament
Between greater and lesser tubercle of humerus
71
Which arteries are at greatest risk of damage in a shoulder dislocation?
Anterior and posterior humeral circumflex arteries
72
What is Erb's palsy?
Upper brachial plexus injury- will affect shoulder joint function
73
Which is the only rotator cuff muscle that does not have a role in external rotation of the shoulder?
Subscapularis- internal rotation
74
What are the static stabilisers of the shoulder joint?
Glenoid labrum= fibrocartilage ring that deepens the glenoid fossa by about 50%
Capsule
Glenohumeral ligaments = reinforce joint capsule
Extra-capsular ligaments = form coraco-acromial arch
Negative intra-articular pressure = negative pressure sucks in glenoid
75
What are the dynamic stabilisers of the shoulder joint?
Rotator cuff muscles = SITS, (no. 7,8,9,10) surround the shoulder joint, attaching to the tubercles of the humerus, whilst fusing with the joint capsule. The resting tone of these muscles act to pull the humeral head into the glenoid cavity
Biceps brachii
Muscles crossing the shoulder - pectoralis major, latissimus dorsi etc.
76
What position are clavicular fragments likely to be displaced in a mid-clavicular fracture?
Lateral fragment
Inferiorly- weight of arm
Medially- pec major attaches here and adducts upper limb
Medial fragment
Superiorly- action of sternocleidomastoid
77
Which parts of the brachial plexus are at most risk of injury when the clavicle is fractures?
Trunks and divisions- lie posterior to the fracture point of the clavicle
78
Explain how you would assess a patient for damage to the brachial plexus caused by clavicular fracture.
Minimal movement of shoulder and arm to avoid damage to the neurovascular structures by the fragments during examination.
Sensation - test dermatomes C5-T1
Motor- test movements whilst stabilising the shoulder and arm
79
Which artery and vein are at most risk of damage from a clavicular fracture?
```
Anterior to posterior:
Clavicle
Subclavian vein
Subclavian artery
Trunks of brachial plexus
```
80
In a proximal clavicular fracture, auscultation of the chest must be performed and a chest X-ray may also be needed. What rare but important complication needs to be excluded?
Pneumothorax
81
What is the coracoacromial arch and what is its role at the shoulder when falling on an outstretched hand?
Coraco-acromion ligament between the inferior surface of the acromion and the coracoid process forms an osseo-ligamentous structure.
Functions:
-protective arch so prevents superior displacement of the head of the humerus from the glenoid cavity of the scapula
82
What structures can be affected by a fracture of the surgical neck of the humerus?
Surgical neck is a constriction beneath the tubercles of the greater tubercle and lesser tubercle
May cause damage to:
- axillary nerve
- posterior circumflex humeral artery
These go through the quadrangular space. The surgical neck of the humerus is the lateral border of this space.
83
Which nerve is most likely to be injured in mid-shaft humeral fracture and why?
Radial nerve
| The nerve runs in the radial groove on the posterior surface of the shaft of the humerus
84
```
In a patient there is...
Flattening/squaring of their shoulder.
A prominent coracoid process.
Arm is externally rotated and slightly abducted
Diagnosis?
```
Antero-inferior dislocation of the shoulder
85
What is a bankart lesion and when does it occur?
Can occur due to an anterior shoulder dislocation
Avulsion (pulling/tearing away) of the antero-inferior glenoid labrum at its attachment to the antero-inferior glenohumeral ligament complex. There is a rupture of the joint capsule and inferior glenohumeral ligament injury.
86
What is a Hill-sachs lesion and when does it occur?
Can occur due to an anterior dislocation of the shoulder
A posterolateral humeral head indentation fracture can occur as the soft base of the humeral head impacts against the relatively hard anterior glenoid.
87
Acromioclavicular dislocations can be categorised with the rockwood classification. What injury are the lower and higher classes associated with?
Lower- Damage to acromioclavicular ligament
| Higher-Damage to coracoclavicular ligament and acromioclavicular ligament
88
A patient has an undisplaced humeral fracture. Would surgery usually be considered?
No- bone with heal by normal fracture repair
89
A patient has a displaced humeral fracture. Will surgery be considered?
Yes= may require fixing or joint replacement
| There is bone sitting in the axilla with no blood supply so ischaemic necrosis will occur
90
What complications should be considered in a humeral neck fracture?
Damage to axillary nerve
| Damage to posterior circumflex artery
91
What complications should be considered in a mid-shaft humeral fracture?
Damage to radial nerve which runs in radial groove on posterior surface of humerus
92
How would movement in the arm at the elbow, wrist and fingers be affected in a mid-shaft humeral fracture if the radial nerve had been damaged?
Flexion of elbow normal
No effect or mildly compromised extension of elbow
Poor wrist extension (wrist drop)
Poor finger extension
93
Where do clavicle fractures usually occur?
Middle of third of clavicle/ junction of middle 2/3 and lateral 1/3
94
In which direction to clavicle fragments move in a clavicle fracture? Why?
The lateral fragment is most likely to be displaced medially (overlying the medial fragment) due to the action of pectoralis major adducting the upper limb; and inferiorly due to the weight of the upper limb pulling downwards on the fracture fragment. The medial fragment is likely to be displaced superiorly by the action of sternocleidomastoid, exacerbating the degree of non-alignment of the fracture fragments.
95
What complications should be considered in a clavicle fracture?
Brachial plexus damage - roots and trunks
Subclavian artery damage
Subclavian vein damage
Pneumothorax
96
What is calcific tendinitis and where does it usually occur in the shoulder?
Tendon deposits calcium hydroxyapatite in subacromial space
| This gets in the way when you abduct your arm- if you keep abducting it will burst
97
```
Patient has:
2 day history of pain in shoulder
Rapidly progressive pain
10/10 severity
Resolves in 1 to 2 weeks.
Diagnosis?
```
Calcific tendinitis
Resolves in 1-2 weeks- phagocytes resorb material
98
Patient presents with a 'Popeye muscle'. What has caused this? How is it treated?
Rupture of long head of biceps.
| No treatment- patient would not notice much weakness in upper limb due to action of brachialis and supinator muscles
99
What is the subacromial space and which structures are found here?
Space between the acromion and head of humerus
```
Within this space:
Subacromial bursa
Rotator cuff tendons
Capsule
Long head of biceps
```
100
Which movement can cause exacerbated impingement of soft tissue in the subacromial space?
Abduction
101
Patient has low painful arc
Tenderness over tuberosity
Hawkins test positive
Diagnosis?
Impingement
102
What are the common causes of impingement in the subacromial space?
Tendinitis- swollen long head of biceps and rotator cuff tendons (usually due to overuse)
Bursitis- infection subacromial bursa
This increases friction at the joint especially in the middle of abduction
103
What is painful arc?
Pain in the middle of abduction
20-120 degrees
* Very small gap between acromion and head of humerus, means that things can get trapped at certain points during abduction
* Subscapularis tendon sometimes impinged under CAA, which leads to inflammation and infections (subacromial bursitis)
* Causes specific pain between 50 and 130 degrees abduction
* More likely with repetitive movements, age etc
104
At which joints in the shoulder girdle does osteoarthritis usually occur? (2)
Glenohumeral
| Acromioclavicular
105
Patient has:
Severe, progressive jerk pain in shoulderwhen exerting themselves eg. When catching something that's falling quickly
Progressive stiffness follows
Diagnosis?
Frozen shoulder
| Adhesive capsulitis
106
How are rotator cuff tears treated?
Can sometimes be repaired
| Sometimes requires an allograft
107
What are the effects of ageing on joints? (4)
Variable among individuals, affected by genetic factors, wear and tear
- decreased production of synovial fluid
- thinning of articular cartilage
- shortening of ligaments and a decrease in ligamentous flexibility
- degenerative changes in load-bearing joints
108
Describe the structure and organisation of skeletal muscle.
* Striated
* Multinucleate
* Distinct myofibrils
* T-tubules at z line
* Can be red, white or intermediate
* No cell to cell junctions
* Each cell surrounded by endomysium
* Groups of fibres surrounded by perimysium
* The entire muscle is surrounded by epimysium
109
What is fasciculation?
Involuntary unsynchronised contraction of fascicles.
| Sign of multineurone disease.
110
What is a dermatome?
Area of skin supplied by a single spinal nerve root.
111
Explain the embryonic development of dermatomes.
Paraxial mesoderm is arranged into somites at the 4th week of gestation. Somites are blocks of mesoderm cells around a small cavity. From each somite, dermatomyotome ( from which dermatome and myotome develops) and sclerotome develops.
Dermatomyotome develops in association with a specific neural level of a spinal cord. They take a nerve supply with them from the neural tube as a spinal nerve. Therefore, skin and muscle derived from a single dematomyotome have a common spinal nerve supply.
Nerves grow into the developing limb buds. As the limb bud increases in size, the nerves are dragged along with the structures they innervate eventually producing the adult pattern.
112
Does laceration of a single dorsal spinal nerve root lead to anaesthesia of the entire corresponding dermatomal area?
Each dermatome is named according to the spinal nerve which supplies most of its sensory innervation. In general, contiguous areas of skin are supplied by contiguous spinal nerves. There is considerable overlap between adjacent dermatomes so laceration of a single dorsal spinal nerve root does not usually lead to anaesthesia of the entire dermatomal area.
113
Is there overlap of innervation in areas that are on either side of the axial line?
No
114
Which nerve roots innervate the upper limb?
The upper limb is innervated by the anterior primary rami of spinal nerves
115
What are spinal nerve roots?
They connect each spinal nerve to a 'segment' of the spinal cord.
116
What kind of nerve fibres do dorsal roots contain?
Sensory/afferent nerve fibres only
117
What does the dorsal root ganglion contain?
Cell bodies of the sensory neurones from the periphery
118
What nerves do ventral roots of a spinal nerve contain?
Motor/efferent and autonomic nerve fibres only
119
What is a spinal nerve?
Parallel bundles of axons encased in connective tissue.
It is mixed- contains both motor and sensory nerves
They exist briefly as the pass through the intervertebral foramen- this marks the division between CNS and PNS.
120
How many spinal nerves do we have?
31 pairs numbered according to which level of the vertebral column they emerge from
121
What marks the division between the CNS and PNS?
The intervertebral foramen
122
What marks the division between the CNS and PNS?
The intervertebral column
123
Describe the structure of a spinal nerve?
Endoneurium - surrounds each nerve axon
Perineurium - surrounds a bundle of axons forming a nerve fascicle
Epineurium - surrounds the entire spinal nerve
124
What makes up the spinal canal?
Multiple vertebral foramina
| This is what the spinal cord runs through
125
Where does the spinal cord begin and end?
Begins - inferior region of medulla oblongata
| Ends - conus medullaris at L2
126
What is the cauda equina?
Long roots from inferior segments (lunar, sacral and coccygeal) descend to exit at their respective foramina (looks like a tail)
127
What are the groups of spinal nerve roots?
```
Cervical nerves
Thoracic nerves
Lumbar nerves
Sacral nerves
Coccygeal nerves
```
128
How many pairs of cervical nerves are there?
C1-C8
| One extra nerve than cervical vertebrae
129
How do the cervical nerves exit the vertebral column?
C1-C7 exit above the corresponding vertebrae
| C8 exits between vertebrae C7 and T1
130
How many pairs of thoracic nerves are there?
T1-T12
131
How do the thoracic nerves exit the vertebral column?
Below the corresponding vertebrae
132
How many pairs of lumbar nerves are there?
L1-L5
133
How do the lumbar nerves exit the vertebral column?
Below the corresponding vertebrae
134
How many pairs of sacral nerves are there?
S1-S5
135
How do the sacral nerves exit the vertebral column?
S1-S4 exit via 4 pairs of sacral foramina
S5 exits via the sacral hiatus
136
How many pairs of coccygeal nerves are there?
1
137
How does the coccygeal nerve exit the vertebral column and what accompanies it?
Sacral hiatus with S5
138
Mixed spinal nerves divide into rami. The posterior rami supplies...
Deep muscles and skin of the dorsal trunk
139
Mixed spinal nerves divide into rami. The anterior ramus supplies...
Muscles and skin of the upper and lower limbs and lateral and ventral trunk
140
Spinal nerves give off an meningeal branch. What does this do?
Re-enters spinal canal through the intervertebral foramen.
| Supplies vertebrae, ligaments, blood vessels and meninges.
141
What are the rami communicates?
They are the sympathetic rami that branch off the spinal nerves.
The synapse at gang lions in the sympathetic chain found in the para vertebral column.
142
What does the posterior rami divide into?
Medial and lateral branches
143
What is a myotome?
Myotome = group of muscles innervated by a single spinal nerve root
144
What is a motor unit?
A motor unit is a motor neurone and the skeletal muscle fibres it innervates.
145
One spinal nerve root contains the neurones of only one motor unit.
True or false?
False
| 1 spinal nerve contains the neurones of many motor units
146
How does the size of a motor unit determine the movements it may perform?
In general terms the smaller the motor unit, the more precise movements it may perform.
147
What is the axial line?
Junction of two dermatomes supplied from discontinuous spinal levels.
148
What are the pre-axial and post-axial boundaries marked by?
They are marked by veins
- UPPER LIMB cephalic pre-axial and basilic post-axial
- LOWER LIMB long saphenous pre-axial and short saphenous post-axial
149
What is the cutaneous distribution of a peripheral nerve?
The area of skin that a peripheral nerve innervates. It often contains nerve fibres from several spinal nerve roots.
150
Which viral infection almost always affects the skin of a single dermatome?
Herpes Zoster - shingles
Reactivation of Varicella zoster virus (chickenpox)
The virus travels through a cutaneous nerve and remains dormant in a dorsal root ganglion after chickenpox.
When host is immunosuppressed, VZV reactivates and travels through peripheral nerves to the skin of a single dermatome
151
During surgery to remove a lump from the axilla, a nerve originating from the lateral cord of the brachial plexus is injured.
Which of the following nerves originates from the lateral cord of the brachial plexus:
Ulnar
Medial pectoral
Radial
Lateral pectoral
Thoracodorsal
Which muscle does it innervate?
Lateral pectoral nerve
Pectoralis major
152
A rugby player sustains a complete spinal cord transection at spinal level C8. What is likely to be seen in the patient?
The neural level of the injury is defined as the lowest level of full sensation and function.
The interossei will be completely paralysed.
The intrinsic muscles of the hand are supplied by the T1 myotome.
The C8 myotome will be functioning and everything below that will be paralysed.
153
A 22 year old motorcyclist is involved in a high speed road traffic collision and thrown off from his bike. He immediately realises that he cannot feel or move his legs. On sensory examination, he has anaesthesia of the lower limbs and abdomen from 1.5cm below the level of the umbilicus. What is the most likely level of his neural injury?
T10
The T10 dermatome is at the level of the umbilicus
154
A 26 year old rugby player sustains a cervical fracture during a scrum, with impingement of bony fragments onto his spinal cord. One examination of his upper limbs, elbow flexion is intact bilaterally but supination is lost. He has no active elbow extension, wrist extension or wrist flexion and no active movement of his fingers. Function of the muscles in the torso and trunk as well as the legs is lost.
What is the most likely level of neural injury?
C5
The patient has preserved elbow flexion, suggesting that either C5 or C6 is intact.
Supination, wrist flexion, wrist extension is lost suggesting C6 is damaged.
All other movements supplied by spinal nerves below are lost.
155
What are the articulating surfaces of the elbow joint?
Trochlear notch of the ulna and trochlea of the humerus (makes up most of the hinge joint)
Head of the radius and capitulum of the humerus
156
Fractures affecting the radius often affect the ulna and vice versa. Why?
The radius and ulna are attached by the interosseous membrane. The force of trauma to one bone can be transmitted to the other bone via this membrane. Thus fractures, of both the forearm bones are not uncommon.
157
What does the radius articulate with?
* Head of radius articulates with the capitulum of the humerus at the elbow joint
* Head of radius articulates with the radial notch of the ulna at the proximal radioulnar joint
* Distal end of the radius articulates with the scaphoid and lunate carpal bones at the wrist joint
* Distal end of the radius articulates with the styloid process of ulna at the distal radioulnar joint
158
What does the ulna articulate with?
* Trochlear notch articulates with trochlea of the humerus at the elbow joint
* Radial notch articulates with head of radius at the proximal radio-ulnar joint
* Styloid process articulates with distal radius forming the distal radio-ulnar joint
159
What does the humerus articulate with?
* Head of the radius articulates with the glenoid fossa of the scapula at the glenohumeral joint
* Capitulum articulates with the head of the radius at the elbow joint
* Trochlea articulates with trochlear notch of ulna at the elbow joint
160
What three joints make up the elbow joint?
Hinge joint - ulno humeral
Radio humeral - ball and socket
Trochoid - proximal radioulnar joint
161
What type of a joint is the elbow joint?
Synovial hinge joint
162
What prevents hyperextension of the elbow joint?
When the elbow is fully extended, the olecranon of the ulna sits firmly in the olecranon fossa of the humerus, restricting any further extension.
163
Why is flexion of the elbow limited to the point when your forearm and arm muscles make contact?
When the elbow is fully flexed, the radial head sits firmly in the radial notch and the coronoid process of the ulna sits firmly in the coronoid notch of the humerus, restricting any further flexion
164
What is Cubitus Varus and Cubitus Vargus?
| Which is a cosmetic problem and which is a functional problem?
Cubitus Varus - forearm and hands are angled medially towards body
COSMETIC PROBLEM
Common cause is a supracondylar fracture not healing properly
Cubitus Vargus- forearm and hands are angled greater than 5-15 degrees away from the body
FUNCTIONAL PROBLEM - can stretch the ulnar nerve leading to ulnar nerve palsy
165
What structures contribute to the stability of the elbow joint?
Fibrous capsule
Ligaments (radial collateral ligament, ulnar collateral ligament and anular ligament)
Muscles
166
What is the difference between dislocation and subluxation?
Dislocation - articulating surfaces have completely lost contact with one another
Subluxation - articulating surfaces have partially lost contact from one another
167
What type of fall is most likely to result in an elbow dislocation and why?
Fall on a flexed elbow.
The distal end of the humerus is driven through the weakest part of the joint capsule on the anterior side resulting in a posterior dislocation.
The ulnar collateral ligament is usually torn.
168
Are elbow dislocation is named by the position of the ulna and radius or the humerus?
Ulna and radius
169
What is the most common dislocation of the elbow joint? Which nerve can be injured?
Posterior
| Ulnar nerve
170
What is a fat-pad sign?
A fracture will always result in haemorrhage.
Bleeding is usually contained within the capsule so fluid accumulates within it.
As fluid accumulates, the fat pad is lifted away.
This is a fat pad sign.
171
What kind of a fall is a common cause of a clavicular fracture?
Fall on an outstretched arm
172
Which nerve is most likely to be damaged in a supraepicondylar fracture of the humerus?
Median nerve
173
Which nerve is most likely to be damaged in an avulsion of the medial epicondyle of the humerus?
Ulnar nerve
174
Wrist-drop
Unable to flex elbow
Loss of sensation in lateral upper arm, posterior upper arm, a strip in the posterior forearm and dorsal lateral 3 and a half digits and associated palm area.
Which nerve is damaged and where?
What is the likely cause?
Radial nerve in axilla due to:
- dislocation of shoulder joint
- fracture of proximal humerus
- pressure on the radial nerve
175
Wrist drop
Extension of elbow is fine
Sensation in dorsal lateral 3 digits and associated palm area is lost
Which nerve is damaged?
Where is it damaged and what is likely to have caused it?
Radial nerve
At level of radial groove
Elbow extension is not compromised because branches to the long head and lateral head of the biceps are given off before the radial groove. Anconeus is paralysed but triceps brachiiis the main extensor so there is no significant impact on elbow extension.
Humeral-shaft fracture
176
Radial head is posteriorly dislocated and damages the radial nerve. How would the patient present?
Weakened extension of wrist but wrist drop does not occur branch to extensor carpi radialis unaffected
Majority of posterior forearm muscles are affected so may be unable to extend the fingers
Sensation in dorsal lateral 3 fingers and associated palm area lost but sensation in posterior forearm unaffected
177
Stabbing or laceration of the forearm is likely to affect which branch of the radial nerve?
How would the patient present?
Superficial branch
| Sensory loss affecting dorsal 3 and a half digits and associated palm area
178
Hand of benediction
Wasted thenar eminence
Can flex wrist and pronate forearm
Which nerve is damaged and where is it likely to be damaged?
Median nerve
Wrist proximal to flexor retinaculum after carpal tunnel
179
How would a patient present if they damaged the median nerve in a supraepicondylar fracture?
Flexors of wrist and pronators of forearm and flexors of the thumb paralysed except flexor carpi ulnaris and medial half of flexor digitorum profundus so
weakened wrist flexion and able to flex only medial two digits on making a fist ---> hand of benediction
Thenar eminence wasted
Lack of sensation in lateral palm and anterior lateral 3 and a half digits, fingertips and nail beds
180
What is a common cause of carpal tunnel syndrome?
Thickened tendons and tendon sheaths
181
Numbness, tingling and pain in lateral 3 and a half digits and associated palm area
Pain radiates to forearm
Wakes patient up at night and worse in mornings
Diagnosis?
Carpal tunnel syndrome
182
In a fracture of the medial epicondyle, which nerve is likely to be damaged and how would this present?
Ulnar nerve
Flexion of wrist can occur but is accompanied by abduction
Cannot abduct or adductor fingers - cannot grip paper between fingers
Movement of little and ring fingers is greatly reduced
Loss of sensation over medial 1 and a half digits and associated palmar and dorsal area
183
How would presentation be similar and different if the ulnar nerve is damaged at the elbow and damaged at the wrist?
Ulnar claw not as prominent in damage at the elbow because flexor digitorum profundus is paralysed.
Sensory function is completely lost in damage at the elbow whereas sensory function only over the palmar area is lost at the wrist.
Flexion of the wrist is accompanied with abduction in damage at the elbow whereas flexion of the wrist is normal in damage at the wrist.
In both, patient will be unable to hold paper between their fingers.
184
Describe ulnar claw.
Hyper-extension of MCP joints of medial two digits due to paralysis of medial 2 lumbricals and unopposed action of the extensor muscles
Flexion at ICP joints (if lesion has occurred close to the elbow, this might not be evident as the flexor digitorum profundus will be paralysed.
185
Damage of which nerve results in:
1. Ulnar claw
2. Hand of benediction
3. Wrist drop
1. Ulnar nerve
2. Median nerve
3. Radial nerve
186
What is the difference between ulnar claw and hand of benediction?
Both appear the same with medial two digits flexed at MCP joint and IP joints, lateral 3 digits fully extended.
Hand of benediction - occurs when trying to make a fist (damage to median nerve)
Ulnar claw - on relaxation (damage to ulnar nerve)
187
A stab wound to the axilla damages the musculocutanoeus nerve. Is any motor function of any of the joints in the upper limb completely lost?
Where is sensation lost?
No.
Flexion at shoulder is weakened but can still occur due to pectoralis major
Flexion at the elbow is weakened but can still occur due to brachioradialis
Supination of the forearm is weakened but can still occur due to supinator
Sensation lost in lateral forearm
188
What fracture is likely to be caused due to a fall on a flexed elbow?
What are its complications?
Supraepicondylar fracture - transverse fracture spanning between the epicondyles
Damage to structures travelling in cubital fossa
Brachial artery- Interference to blood supply of the forearm
Volkmann's ischaemic contracture
Median nerve damage
weak wrist flexion, forearm supinate, loss of thumb flexion, thenar eminence wasting, lateral 2 lumbricals paralysed - loss of flexion at MCP and ICP joints in lateral 2 fingers
Radial nerve damage
Wrist drop
189
Where would you palpate to feel the brachial pulse?
Medial to the biceps tendon
190
Which vein is commonly used for venepuncture?
Median cubital vein - connects the basilica and cephalic veins
191
Describe the blood supply of the hand.
The ulnar artery supplies the anterior aspect of the forearm. It enters the hand anteriorly to the flexor retinaculum and laterally to the ulnar nerve.
The radical nerve supplies the posterior aspect of the forearm. It enters the hand dorsally, crossing the floor of the anatomical snuffbox. It turns medially and moves between the heads of adductor pollicis.
* superficial palmar arch - arises from the terminal ulnar and superficial palmar branches of the radial artery
* deep palmar arch - arises from the deep palmar branch of the ulnar artery and a branch of the radial artery
192
Localised pain in the anatomical snuffbox is most likely due to...
Fracture of the scaphoid
Scaphoid has a unique blood supply, distal to proximal. A fracture of the scaphoid can disrupt blood supply to the proximal portion which is an emergency- failure to revascularise can result in avascular necrosis and future arthritis
193
What does the anterior interosseous nerve supply?
Deep muscles of the forearm
Pronator quadratus
Flexor pollicis longus
Flexor digitorum profundus (lateral part)
194
There is a congenital syndrome where the radius and ulnar are joined together so pronation and supination is affected. Why does this often go unnoticed and not have an impact on the patients movement?
Shoulder can compensate for some loss of pronation and supination
195
What can a strong pull on the forearm, especially in children cause?
Can pull the head of the radius out of the anular ligament resulting in dislocation of the proximal radio-ulnar joint
196
What can cause subcutaneous bursitis of the elbow?
Repeated friction and pressure on the bursa (leaning on your elbow) because this bursa lies superficially
197
What can cause subtendinosus bursitis?
Repeated flexion and extension of the forearm - usually flexion as more pressure is put on the bursa
198
What is usually the cause of an anterior dislocation of the humerus?
Excessive lateral rotation or extension of the humerus- hence, the humeral head is forced anteriorly and inferiorly into the weakest part of the joint capsule
199
A young child falls on a hand with the elbow flexed. What is injury is likely to occur?
Elbow dislocation - distal end of the humerus driven through the weakest part of the joint capsule on the anterior side. The ulnar collateral ligament is usually torn and there can be ulnar nerve damage.
Mot are posterior - named by position of ulna and radius
200
Where is the weakest point in the shoulder and elbow joint capsule?
Anterior part of both joint capsules
Therefore, the most common dislocations are:
Anterior dislocations of the shoulder joint
Posterior dislocations of the elbow joint
201
```
FOOSH
Pain in lateral elbow
Modest swelling
Loss of range
Fat pad sign
```
Which bone is likely to be fractured?
Radial neck/head fracture- radial head is forced into capitulum of humerus
202
FOOSH
Pain and swelling in distal forearm
Dinner fork deformity
Diagnosis?
Colles' fracture of distal radius
203
What is the difference between Colles' fracture and Smith's fracture?
Colles' fracture
Dorsal displacement and angulation, shortening
Smith's fracture
Palmar displacement and angulation, shortening
204
A fracture of the distal radius is caused by falling onto the back of the hand. The distal fragment wrist bones and hand bones are placed anteriorly. What is the name given to this type of fracture?
Smith's fracture
205
FOOSH
Delayed presentation of pain in anatomical snuffbox
What could be the cause?
Scaphoid fracture
206
Hy does a scaphoid fracture need to be reduced quickly?
Blood supply to scaphoid is distal to proximal
Blood supply yo proximal part can be cut off causing it to undergo avascular necrosis. Patients with a missed scaphoid fracture are likely to develop wrist arthritis in later life
207
Child swung from their arms
No longer pronates
What is likely to have happened?
Subluxation of radius head from annular ligament
208
Symmetric polyarthropathy with morning stiffness affecting small and large joints
Nodules present in elbow, fingers and forearm
Diagnosis?
Rheumatoid arthritis
209
Is joint replacement more likely to be considered in the management of rheumatoid arthritis or osteoarthritis?
Rheumatoid arthritis
210
What is tennis elbow and golfer's elbow?
Tennis elbow
Overuse strain of the extensors in the forearm
Degenerative tendinopathy of the common extensor origin = lateral epicondyle
Results in pain here
Golfers elbow
Overuse strain of the flexors in the forearm
Degenerative tendinopathy of the common flexor origin = medial epicondyle
Results in pain here
211
Patient has a soft, cystic lump on elbow which transluminates
Diagnosis?
Olecranon bursitis - repeated friction and pressure on this bursa can cause it to become inflamed
212
White material resembling toothpaste coming from soft tissues such as ear, elbow and achilles tendon. What could be the cause?
Gouty tophi
213
What is cubital tunnel syndrome?
Compressive neuropathy of ulnar nerve at elbow
Parasthesia, numbness and weakness in ulnar 1 and a half digits
Hypersensitive 'funny bone'
214
When classifying a fracture, what should be included?
```
Side of the body
Name of the bone that is fractured
Part of the bone that is fractured
Fracture pattern
Whether it is articular/extra-articular
Whether fragments are displaced or not
Whether the fracture is simple or compound or complicated
```
215
What is the difference between an extraarticular and intraarticular fracture?
Intraarticular fractures are those in which the fracture line extends into the joint space.
Extraarticular fractures are those in which the fracture line does not enter the joint space.
216
What is the difference between an open and closed fracture?
Closed fracture = skin overlying fracture is intact
Open fracture = skin overlying fracture is broken- bone fragment within breaks out through skin or force from outside penetrates both skin and bone
217
What is a complicated fracture?
Involving damage to neurovascular structures or internal organs
218
What is a fracture resulting in multiple fragments called?
Comminuted fracture
219
What is a fracture that passes at right angles to the shaft of the long bone called?
Transverse fracture
220
What type of fracture does a twisting injury results in?
Spiral fracture
221
What is a compression fracture?
Ends of a bone are driven into one another- typically occurs in vertebral bodies
222
What is an avulsion fracture?
An avulsion fracture is an injury to the bone in a location where a tendon or ligament attaches to the bone. When an avulsion fracture occurs, the tendon or ligament pulls off a piece of the bone. Avulsion fractures can occur anywhere in the body, but they are more common in a few specific locations.
223
What is a green stick fracture?
A greenstick fracture is a fracture in a young, soft bone in which the bone bends and breaks. Greenstick fractures usually occur most often during infancy and childhood when bones are still ossifying by endochondral ossification.
224
Describe the composition of cartilage.
Extracellular matrix - collagen fibrils and proteoglycan monomers with a ground substance
Chondrocytes
225
Describe the composition of the extracellular matrix in cartilage.
--->Proteoglycan monomers:
Core protein
Glycosaminoglycans (GAGs) eg. Hyaluronic acid
---> type II collagen
226
Describe the composition of bone.
Extracellular matrix:
- calcium and phosphate store
- type I collagen
Cells:
- osteoprogenitor cells - derived from mesenchymal cells and give rise to osteoblasts
- osteoblasts - secrete the extracellular matrix of bone, once the cell is surrounded with its secreted matrix, it is an osteocyte
- bone-lining cells - remains on surface when there is no active growth
- osteoclasts - bone resorting cells present on bone surfaces where bone is being removed, remodelled or where bones have been damaged
227
What are the functions of the skeleton?
- support
- protection
- movement
- mineral and growth factor storage
- haematopoiesis
228
What is the function of the nutrient artery?
Supplies the marrow with blood
| It enters at the diaphysis via the nutrient foramen
229
Are sesamoid bones mainly made of spongy bone or compact bone?
Spongy bone
230
Describe blood supply to bones.
Nutrient artery = enters diaphysis via nutrient foramen
Periosteal arteries =supplies periosteum and outer third of the cortex
Epiphyseal artery - supplies epiphysis
Metaphyseal arteries - enters metaphysis at site of attachment of capsule
231
What happens to the epiphyseal and metaphyseal arteries after ephyseal fusion?
They anastomose
232
What are the common causes of avascular necrosis of bone.
- fracture
- dislocation
- steroid use
- radiation
- decompression sickness
233
What does avascular necrosis result in?
Collapse of necrotic segment and secondary osteoarthritis
234
What nerves supply a joint capsule?
Hilton's law
The nerves supplying the joint capsule also supply the muscles moving the joint and the skin overlying the insertions of these muscles.
235
What is a joint?
Articulation between two or more bones
236
How are joints structurally classified?
1. Fibrous
2. Cartilaginous
3. Synovial
237
Describe the structure of a fibrous joint.
Lack a synovial cavity
| Articulating bones are held closely together by fibrous connective tissue - permit little or no movement
238
What type of a joint is the radioulnar interosseous membrane?
Fibrous joint
239
Describe the structure of a cartilaginous joint.
Lack a synovial cavity. Articulating bones are tightly connected by cartilage which permits little or no movement.
240
What is the difference between primary and secondary cartilaginous joints?
Primary cartilaginous joint - hyaline cartilage eg. 1st sternocostal joint
Secondary cartilaginous joint - hyaline cartilage with a pad of fibrocartilage between them eg. Pubic symphysis
Limited movement is permitted, depending on the thickness of the fibrocartilage pad which can be compressed or stretched.
241
Describe the structure of a synovial joint.
Articular cartilage - hyaline cartilage
Fibrous capsule
Synovial membrane
Synovial fluid
242
What is the function of articular cartilage in a synovial joint?
Smooth low friction movement
| Resists compression
243
Describe the structure and function of the fibrous capsule in a synovial joint.
Made of collagen in longitudinal and interlacing bundles
Completely encloses the joint excerpt where interrupted by synovial protrusions
Stabilises the joint, permits movement, resists dislocation
244
Does the synovial membrane cover articular cartilage, intra-articular discs or menisci?
No
245
How are synovial joints supplied with blood?
Periarticular arterial plexus
Synovial membrane has a rich blood supply because articular cartilage is avascular so must be supplied with nutrients and oxygen from the synovial fluid.
246
What movements can occur at a planar joint?
Sliding or gliding movements
247
What movements can occur at a hinge joint?
Uniaxial - flexion and extension
248
What movements can occur in a condyloid joint?
Biaxial joint - oval shaped condolence of one bone sits on elliptical cavity of another
Movements: flexion, extension, abduction, adduction
249
What movements occur at a pivot joint?
Rotation
250
What factors affect the stability and range of motion at synovial joints?
- structure and shape of articulating bones
- strength and tension of joint ligaments
- arrangement and tone of muscles
- apposition of neighbouring soft tissues
- hormones eg. Relaxin in pregnancy
- use/disuse
251
What causes cracking of the joints?
* Bones are pulled away from each other
* Synovial cavity expands
* Synovial fluid volume stays constant
* Partial vacuum produced
* Gases dissolved in synovial fluid are pulled out of solution
* Makes a popping sound
252
What is a bursa?
Sac lined with synovial membrane
Filled with synovial fluid
Communicating or non-communicating with \jooint cavity
Reduces friction
253
What is a tendon sheath?
Elongated bursa wrapped around a tendon
254
What are the effects of ageing on joints?
- Decreased production of synovial fluid
- Thinning of articular cartilage
- Shortening of ligaments and a decrease in ligamentous flexibility
- Degenerative changes in load-bearing joints
255
What is arthritis and what are the symptoms common to all types?
Inflammation and stiffness of a joint.
Symptoms:
- pain
- swelling
- stiffness
- signs of erythema
- swelling deformity
- tenderness
- reduced range of movement
- commonly manifests to abnormal gait
256
What are the x-ray features of osteoarthritis?
L - loss of joint space
O - osteophytes (bony spurs due to new bone formation at the margins of arthritic joints)
S - subchondral sclerosis (a thin layer of increased bone density beneath the
articular cartilage)
S - subchondral cysts (fluid filled sacs in the bone beneath the articulating cartilage).
257
What happens in osteoarthritis?
In osteoarthritis we see wearing away of the articular surfaces with consequent loss of joint space and ultimately bone grinding on bone, generating severe pain and loss of range of movement.
258
What happens in rheumatoid arthritis?
Autoimmune disease
Autoantibodies (rheumatoid factor) attack the synovium. This causes synovial inflammation (pannus)
This results in joint erosion and deformity.
Damage to eyes, skin, lungs, heart and blood vessels, kidneys and blood- results in anaemia of chronic disease
Peak age 40-50
Women>men
259
What are the x-ray features of rheumatoid arthritis?
L - loss of joint space
E - erosions in non-cartilage protected bone
S - soft tissue swelling
S - soft bones (periarticular osteopenia)
S - subluxation and gross deformity
260
Which of the following statements about compact and spongy bone is true? A) Compact bone is made of trabeculae and resists stresses from many directions. B) Spongy bone is made of trabeculae and resists stresses from only a few directions. C) Spongy bone is made of osteons and resists stresses from many directions. D) Compact bone is made of osteons and resists stresses from only a few directions.
D
Compact bone forms the hard external layer of all bones and surrounds the medullary cavity. It provides protection and strength to bones. Compact bone tissue consists of units called osteons or haversian sytems. Osteons are cylindrical structures that contain a mineral matrix of living osteocytes connected by canaliculi which transport blood. They are aligned parallel to the long axis of bone. Each osteon consists of lamellae, layers of compact matrix that surround a central canal which contains the bones blood vessels and nerve fibres. Osteons in compact bone are all aligned in the same direction of stress, helping the bone resist bending or fracturing. Therefore, compact bone tissue is prominent in areas of bone at which stresses are applied only in a few directions.
261
Which of the following are incapable of undergoing mitosis?
A) Osteoblasts and osteoprogenitor (osteogenic) cells
B) Osteoprogenitor cells and osteocytes
C) Osteoblasts and osteocytes
D) Osteoprogenitor cells and osteoclasts
C
Osteoblast - bone cell responsible for forming new bone, found in growing portions of bone including the periosteum and endosteum. Do not divide, synthesise and secrete collagen and calcium salts
Osteocytes - as the secreted matrix surrounding the osteoblasts calcifies, the osteoblast becomes trapped within it and changes in structure becoming an osteocytes. Each osteocytes is coated in a space surrounded by bone tissue. They maintain the mineral concentration of the matrix by secretion of enzymes. Lack mitotic activity, communicate with each other and receive nutrients via long cytoplasmic processes that extend through canaliculi found in the bone matrix.
262
What is the template that immediately precedes intramembranous and endochondral ossification?
Intramembranous - mesenchyme
| Endochondral - chondrocyte
263
Give an example of the 3 types of structural joints.
Fibrous joint - radioulnar interosseous membrane, inferior tibiofibular joint, sutures of the skull
Cartilaginous -
Primary - 1st sternocostal joint, epiphyseal growth plates
Secondary - pubic symphysis
Synovial joint - glenohumeral joint...
264
What type of joint is the radiocarpal joint?
Condyloid/ellipsoidal synovial joint
265
The superficial palmar arch is superficial to...
The long flexor tendons
266
The deep palmar arch is deep to...
The long flexor tendons
267
From which artery is an arterial blood gas commonly taken from?
Radial artery
268
In an injury to the nail, what determines whether the nail will grow back or not?
If the germinal matrix is preserved, the nail will grow back.
269
What is the difference between thin skin and thick skin?
Thick skin has densely compacted layers and the epidermis indents into the dermis. Eg. Palm of the hand
Whereas
Thin skin has sparse layers and the epidermis does not indent into the dermis.
270
How are flexor digitorum superficialis and flexor digitorum profundus supplied with blood?
They do not have a direct blood supply but have vinculum coming from the bone to supply them and to allow the tendon to move.
271
What anatomical structure prevents the bowstring effect from happening to the long flexor tendons in the digits?
Each tendon has a pulley attached to the tendon sheath to keep the tendon close to the bone and increase range of movement.
272
What test is taken before an arterial blood gas and why?
Before drawing blood for an arterial blood gas, an Allens test is taken to ensure that blood flow to your hand is normal
Pressure is applied to the radial and ulnar arteries in the wrist so blood flow to the hand is stopped. The hand becomes cool and pale. Blood is then allowed to flow through the artery that will not be used to collect the sample. This is usually the ulnar artery since arterial blood gases are usually taken from the radial artery
273
Why are the fingers curled at rest?
Tone of the flexor muscles is greater than tone of extensors at rest.
274
What is tenosynovitis?
Inflammation of the tendon and synovial sheath. How far the infection spreads from the digits depends on variations in their connections with the common flexor sheath.
275
What is De Quervain's tenosynovitis?
Inflammation of the tendons of abductor pollicis longus and extensor pollicis brevis as they are in the same tendinous sheath.
276
What are the common causes of tenosynovitis?
Injuries such as a puncture of a finger by a contaminated object
277
What is Finkelstein's test used for?
Finkelstein's test is used to diagnose De Quervain's tenosynovitis in people who have wrist pain. To perform the test, the examining physician or therapist grasps the thumb and ulnar deviates the hand sharply. Pain is felt here.
278
At which joints in the hand is osteoarthritis and rheumatoid arthritis common?
Osteoarthritis
First carpometacarpal joint
Distal interphalangeal joints (heberden's nodes)
Rheumatoid arthritis
Metacarpophalangeal joints
Proximal interphalangeal joints
279
What condition can rheumatoid arthritis in the hands lead to?
Tenosynovitis
| Rheumatoid arthritis can cause a tendon's synovial sheath to become inflamed.
280
What is boxer's fracture?
A fracture of the 5th metacarpal neck. Usually caused by a clenched fist striking a hard object. The distal part of the fracture is displaced posteriorly, producing shortening of the affected finger.
281
Why is tingling not felt in the lateral palmar surface of the hand in carpal tunnel syndrome?
The palmar cutaneous branch of the median nerve arises in the forearm so is not affected.
282
How can carpal tunnel syndrome be tested for?
* Tinel's sign - Can be tested by tapping nerve in carpal tunnel to elicit pain
* Phalen's manoeuvre - Can also be tested by holding the wrist in forced flexion for 60 seconds to elicit pain
283
What palsy can frequent grasping of bike handlebars cause?
Handlebar palsy - compression of the ulnar nerve in Guyon's canal
Results in some degree of ulnar claw and parasthesia over the palmar aspect of the medial 1 and a half digits (dorsal branch for sensory innervation to the dorsal skin arises before the canal)
284
What is dupuytrens disease?
Dupuytrens contracture is a disease of the palmar fascia resulting in progressive shortening, thickening and fibrosis of the palmar fascia and palmar aponeurosis. This pulls the fourth and fifth digits into partial flexion at the metacarpophalangeal and proximal interphalangeal joints.
285
What happens in reflex sympathetic dystrophy?
1. Original injury initiates a pain impulse carried by sensory nerves to the CNS
2. The pain impulse in turn triggers an impulse in the sympathetic nervous system that returns to the original site of injury.
3. The sympathetic impulse triggers the inflammatory response causing the vessels to spasm leading to swelling and increased pain.
4. The pain triggers another response establishing a cycle of pain and swelling.
286
What kind of a joint is the radio-ulnar joint?
Trochoid (pivot) joint
287
What kind of joints are the MCP joints?
Biaxial condyloid synovial joints
288
What kind of joints are the interphalangeal joints?
Uniaxial synovial hinge joints
289
What are the two types of compartment syndrome?
Acute compartment syndrome:
happens suddenly, usually after a fracture or severe injury
is a medical emergency and requires urgent treatment
can lead to permanent muscle damage if not treated quickly
Chronic compartment syndrome:
happens gradually, usually during and immediately after repetitive exercise (such as running or cycling)
usually passes within minutes of stopping the activity
is not a medical emergency and doesn't cause permanent damage
290
What movement is likely to cause anterior dislocation of the shoulder?
Extension and lateral rotation
291
What are the causes of impingement?
- calcific tendinitis
- tendinitis
- osteoarthritis
- subacromial bursitis
- rotator cuff tear
292
What can cause compartment syndrome?
Trauma to muscles or vessels in compartments from:
- burns
- sustained intense use of muscles
- blunt trauma
These produce haemorrhage, oedema and inflammation of the muscles.
293
Which styloid process is usually fractured in a Colle's fracture?
Styloid process of ulna
294
The styloid of the radius or ulna projects more distally?
Radius
295
On yourself, feel the hook of the hamate bone, just distal to the pisiform.
You will need to palpate deeply for this. Which nerve lies in a canal (Guyon’s canal) just deep to the hook of the hamate and can become compressed against handlebars whilst cycling, causing paraesthesia?
Ulnar nerve
296
What are likely to be the signs and symptoms of a superficial cut of the wrist?
likely to damage the palmar cutaneous branch of the median nerve (lose sensory innervation to lateral side of palm)
297
What is likely to be the symptoms of a deep cut of the wrist?
Superficial cut = likely to damage the palmar cutaneous branch of the median nerve (lose sensory innervation to lateral side of palm)
Deep = likely to damage median nerve in carpal tunnel, could damage radial and ulnar artery (lose innervation to LOAF and innervation to the lateral 3 and a half digits)
