Week 3 Flashcards by Lucy Cooper

The humerus

Classified as a long bone
Articulations:
-proximal aspect: articulates with the glenoid fossa of the scapula, forming the glenohumeral joint
-distally aspect: articulates with the head of the radius and Trochlear notch of the ulna forming the elbow joint

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Proximal landmarks of humerus

Head: the upper end of the humerus
Anatomical neck: separates the head from the greater and lesser tubercles
The greater tubercle: located laterally, it serves as an attachment site for 3 of the rotator cuff muscles: supraspinatus, infraspinatus, teres minor
The lesser tubercle: smaller, located more medially, it provides attachment for the subscapularis
Intertubercular sulcus: a deep groove which separates the 2 tubercles. The tendon of the long head of the biceps brachii emerges from the shoulder joint and runs through this groove
Lips: the edges of the intertubercular sulcus, pectoralis major, teres major and latissimus dorsi insert on the lips of the intertubercular sulcus
The surgical neck: runs from the tubercles to the shaft of the humerus, frequent site of fracture, axillary nerve and posterior circumflex artery at risk

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Shaft landmarks of the humerus

The deltoid tuberosity: located on the lateral side of the numeral shaft, where the deltoid muscle attaches
The radial groove: a shallow depression that runs diagonally down the posterior surface of the humerus, the radial nerve lies within this groove
Provides attachment for a lot of muscles

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Distal region of humerus

Medial and lateral supraepicondylar ridges: formed by the lateral and medial borders of the distal humerus
Lateral and medial epicondyles: immediately distal to the supraepicondylar ridges
Trochlea: articulates with the trochlea notch of the ulna to form the elbow joint
Capitulum: articulates with the head of the radius to form the elbow joint
Coronoid, radial and olecranon fossae: 3 depressions which accommodate the forearm bones during flexion or extension at the elbow

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What part of humerus articulates with radius

Capitulum
Forms radio-capitellar joint

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What part of humerus articulates with the ulna

Trochlea

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Pectoral girdle

Formed by two bones: the scapula posteriorly and the clavicle anteriorly
These bones are part of the appendicular skeleton
Connect upper limb to axial skeleton

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The clavicle

S-shaped long bone that extends between the manubrium of the sternum and the acromion of the scapula
The medial 2/3 of the shaft of the clavicle are convex anteriorly
The lateral 1/3 is flattened and concave anteriorly
-these curvatures increase the resilience of the clavicle
The clavicle is divisible into 3 regions:
-the sternal end: contains a large facet for articulation with the manubrium of the sternum at the sternoclavicular joint
-the shaft: acts as a point of origin and attachment for several muscles- deltoid, trapezius, subclavius, pectoralis major, sternocleidomastoid and sternohyoid
-the acromial end: contains a small facet for articulation with the acromion of the scapula at the acromioclavicular joint (a gliding synovial joint)

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Surfaces of the clavicle

The superior surface of the clavicle is smooth
The inferior surface of the clavicle is rough has following surface markings:
-Conoid tubercle: near the acromial end, gives attachment to the conoid ligament
-trapezoid line: near acromial end, gives attachment to trapezoid ligament
-Subclavian groove: site of attachment of the subclavius muscle
-impression for the costoclavicular ligament: at the sternal end gives attachment to the ligament binging the 1st rib to the clavicle, limiting elevation of the shoulder

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Scapula

Flat bone
It lies on the posterolateral aspect of the thorax overlying the 2-6/7 rib
The convex posterior surface: divided by the spine of the scapula into the supraspinous fossa and infraspinous fossa
- the infraspinatus muscle originates from the infraspinatus fossa and the supraspinatus muscle originates from the supraspinatus fossa
The concave anterior surface:
-contains a large subscapular fossa, the subscapularis muscle originates from here
The spine of the scapula continues laterally as the acromion
The lateral surface:
-the lateral surface of the scapula faces the humerus
-its the site of the glenoid fossa and therefore the glenohumeral joint, also where teres minor originates
-supraglenoid tubercle located superior to glenoid fossa, the place of attachment of the long head of the biceps brachii
-infraglenoid tubercle located inferior to glenoid fossa, the place of attachment of the long head of the triceps brachii
The coracoid process: projects anterolaterally, pectoralis minor, coracobrachialis, short head of biceps brachii

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Joints of the pectoral girdle

Sternoclavicular joints anteriorly
Acromioclavicular laterally
Glenohumeral joints laterally
Scapulothoracic joint posteriorly: there’s muscular connection between the shoulder girdle and rib cage which is formed by muscles including the trapezius, rhomboids and Serratus anterior

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Sternoclavicular joint

Only articulation between upper limb and axial skeleton
Saddle type synovial joint (high mobility) between clavicle and manubrium
Articulating surfaces: the Sternoclavicular joint consists of the sternal end of the clavicle, the manubrium and part of the 1st costal cartilage
The joint is separated into 2 compartments by the articular discs
Articular disc allows the clavicle and the manubrium to slide over eachother more freely allowing for the rotation and movement in a 3rd axis

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The sc joint is made stable and strengthened by?

The Shoulder muscles
The joint capsule: consists of a fibrous outer layer and inner synovial membrane that produces synovial fluid to reduce friction between the articulating structures
Ligaments:
-Sternoclavicular ligaments (anterior and posterior) these strengthen the joint capsule anteriorly and posteriorly
-interclavicular ligament spans the gap between the sternal ends of each clavicle and reinforces the joint capsule superiorly
-Costoclavicular ligament the 2 parts of this ligament (often separated by bursa) bind at the 1st rib and cartilage inferiorly and to the anterior and posterior borders of the clavicle superiorly

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Acromioclavicular joint

Plane type of synovial joint between the acromial end of clavicle and acromion of the scapula
2 atypical features: the articular surfaces of the joint are lined with fibrocartilage instead of hyaline, the joint cavity is partially divided by an articular disc

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What is the AC joint strengthened by to ensure stability?

The joint capsule
Trapezius muscle: reinforces the posterior aspect of the joint capsule
The acromioclavicular ligament: intrinsic runs horizontally from the acromion to the lateral clavicle
The coracoclavicular ligament : extrinsic:
-trapezoid ligament runs from coracoid process of scapula to the trapezoid line of the clavicle
-vertical conoid ligament- runs vertically from the coracoid process of the scapula to the conoid tubercle of the clavicle

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The shoulder joint/ glenohumeral joint

Ball and socket synovial joint between scapula and humerus
Large mobility at expense of stability
Articulating surfaces:
-articulation of head of humerus with glenoid fossa of scapula
-head of humerus much larger than glenoid fossa
To increase stability the glenoid fossa is deepened by a fibrocartilage rim (increases its surface) called the glenoid labrum

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Factors that contribute to mobility of shoulder joint

Type of joint- ball and socket synovial joint
Bony surfaces- shallow glenoid cavity and large humeral head
Inherent laxity of the joint capsule
The joint capsule is lax, permitting greater mobility (particularly abduction)

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Factors that contribute to stability of shoulder joint

1.Glenoid labrum
2.Ligaments of the shoulder joint:
- glenohumeral ligaments (superior,middle, inferior)
These groups of ligaments form the joint capsule and stabilise anterior aspect of the joint
-coracohumeral ligament: attaches coracoid process to greater tubercle and supports superior part of joint capsule
-coracoacromial ligament: between acromion and coracoid process of scapula forming coracoacromial arch, prevents superior displacement humeral head
-transverse humeral ligament: between two tubercles of humerus, holds tendon of long head of biceps in intertubercular groove
3.Rotator cuff muscles: surround shoulder joint and attach to tuberosities of humerus while fusing with joint capsule, the resting tone of these muscles act to compress the humeral head into glenoid cavity
4.Biceps tendon: acts as a minor humeral head depressor

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Bursae of the shoulder joint

To reduce friction in shoulder joint
5 bursae
3 are contiguous: subacromial, subcoracoid, subscapular
Subdeltoid
Suprascapular

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Subacromial bursa

Located deep to the deltoid and acromion
Superficial to supraspinatus tendon and joint capsule
The subacromial bursa reduces friction beneath deltoid promoting free motion of the rotator cuff tendons

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Subscapular bursa

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Located between the subscapularis tendon and scapula
Reduces wear and tear on the tendon during movement at the shoulder joint

Subcoracoid bursa

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Located deep to the coracoid process

Movements of the shoulder joint

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Extension (upper limb back)- posterior deltoid, latissimus dorsi and teres minor
Flexion (upper limb forewords)- pectoralis major, anterior deltoid and coracobrachialis. Biceps brachii weakly assists in forward flexion
Abduction (away)- first 0-15 degrees is supraspinatus, middle fibres of deltoid do the 15-90, past 90 degrees the scapula needs to be rotated to achieve abduction by trapezius and Serratus anterior
Adduction (towards)- pectoralis major, latissimus dorsi and teres minor
Medial rotation - subscapularis, pectoralis major, latissimus dorsi, teres minor and anterior deltoid
Lateral rotation- infraspinatus and teres minor

Dislocation of the shoulder joint

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Superior displacement of the humeral head is prevented by the coracoacromial arch
Anterior dislocations most prevalent 95%
-usually caused by excessive extension and lateral rotation of the humerus. The humeral head is forced anteriorly and inferiorly
The axillary nerve runs in close proximity to the shoulder joint and around the surgical neck of the humerus and so it can be damaged in the dislocation
Injury to the axillary nerve causes paralysis of the deltoid and loss of sensation over regimental badge area

Winging of the scapula

The Serratus anterior muscle attaches to the costal (anterior) face of the scapula, pulling it against the ribcage The long thoracic nerve innervates the Serratus anterior If this nerve becomes damaged the scapula protrudes out the back when pushing with arm

Aortic supply of upper limbs

Right upper limb: -first branch of the aortic arch, the brachiocephalic artery -brachiocephalic artery then divides into right subclavian and right common carotid artery at level of sternoclavicular articulation -Right subclavian artery supplies right upper limb Left upper limb: - third branch of the aortic arch is the left subclavian artery it supplies left upper limb

Segments of the arterial tree of the upper limb

Subclavian artery: aortic arch to lateral border of 1st rib , sternoclavicular joint and lateral border first rib Axillary artery: lateral border 1st rib and inferior border of teres major muscle Brachial artery: inferior border of teres major and radial tuberosity Ulnar and radial artery: re unite distally as; Deep and superficial palmer arches

Organisation of venous drainage

Superficial Deep Perforating Superficial and deep veins being organised along parallel lines Perforating veins join superficial veins to deep veins one way connection

Superficial veins of upper limb

Drain the skin and superficial structures They have valves that ensure one way passage of blood Conduct venous blood against gravitational pull Cephalic vein (lateral) Basilic vein (medial) Joined by median cubital vein Terminate by joining axillary vein

Deep veins of upper limb

Deep and superficial palmer venous arches Ulnar and radial veins- distal and start from a venous arches Brachial vein- radial tuberosity and inferior border of teres minor Axillary vein- inferior border of teres minor muscle and lateral border of 1st rib Subclavian vein- lateral border of first rib and sternoclavicular joint or lateral border of first rib and aortic arch (left side)

Axial lines of upper limb

Limbs have anterior and posterior axial lines Boundaries between flexor and extensor compartments of the limb are defined by what are known as axial lines These are pre-axial and post-axial lines or borders These borders are conveniently marked out by superficial veins: Cephalic and basilic veins, greater and lesser saphenous veins (lower limb) The boundary line between dermatomes supplied from discontinuous spinal levels is known as the axial line

Clinical importance of venous drainage of upper limb

Lymphoedema Venae puncture Provide sites for: -harvesting blood for analysis -administration of IV drugs -fluid replacement for hydration status of body -blood transfusion

Lymphatic drainage of upper limb

It deploys lymph nodes as follows: -supratrochlear lymph nodes -axillary lymph nodes -infraclavicular lymph nodes Drainage is through two parallel systems: -superficial lymph channels -deep lymphatic channels

Nerve supply to the upper limb

Receives all nerve supply from spinal cord Most of its supply is derived from cervical spinal segments C5-T1 Rest comes from T2 roots Brachial plexus C5-T1 anterior rami: Upper trunk: C5 C6 Middle trunk: C7 Lower trunk: C8 T1 Divisions: anterior (flexor) and posterior (extensor) Cords: medial, lateral, posterior Nerves: radial, musculocutaneous, ulnar, median, axillary

Median nerve lesions

Ape thumb Hand of benediction Pointing index

Ulnar nerve lesions

Ulnar claw hand

Radial nerve lesions

Wrist drop

Other nerves of upper limb

Lateral pectoral Upper subscapular Lower subscapular Dorsal scapular Suprascapular nerve Long thoracic Axillary

What is a dermatome

An area of skin supplied by sensory nerve fibres from a single spinal nerve (neural level)

Sensory nerve territories of upper limb

Sensory divisions of terminal nerves of the brachial plexus supply the skin in territorial domains Known as sensory nerve territories These are not dermatomes

Fibrous joints

Skull sutures Syndesmosis: bones united by sheet of fibrous tissue or ligament or a membrane Gomphosis: joint between tooth and socket. Movement here is pathological

Cartilaginous joints

Primary cartilaginous joints: united by hyaline cartilage usually a temporary joint during growth of a long bone Secondary cartilaginous joints: articular surface coated with hyaline cartilage. Bones united by strong fibrocartilage. Strong joints allowing only slight movements eg between vertebrae

Synovial joints

Provide free movements Specialised features: -articular discs which act as shock absorbers eg in temporomandibular joint -fibrocartilage ring to help deepen the joint eg Glenoid labrum -tendons passing through joint capsule eg biceps brachii

6 common features of synovial joints

Bone ends covered by articular cartilage Joint has a connective tissue capsule Joint cavity Inner surface of capsule lined by synovial membrane Commonly reinforced by ligaments Allow a wide range of movements

What are the shoulder joint ligaments

Acromioclavicular ligament Coracoacromial ligament Coracoclavicular ligament

What are the superficial muscles of the shoulder region

Pectoralis major (lateral and medial pectoral nerves) Deltoid (axillary nerve) Trapezius (accessory nerve) Latissimus dorsi (thoracodorsal nerve)

Pectoralis major

Attached to clavicle, sternum and upper ribs, tendon runs in intertubercular groove of humerus

Deltoid

From clavicle, acromion and spine of scapula to deltoid tuberosity Facilitates flexion, extension, abduction and medial and lateral rotation

Trapezius

From vertebral column and external occipital protruberance to clavicle, acromion and spine of scapula Facilitates bracing and shrugging shoulders

Latissimus dorsi

From thoracolumbar fascia, iliac crest, lower 6 thoracic vertebrae and lower 3 or 4 ribs. Tendon lies in intertubercular groove Facilitates extension, Adduction and medial rotation

Week 3 Flashcards

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