Functional and clinical anatomy of the shoulder Flashcards
What are the 3 bones which make up the shoulder?
- Clavicle
- Humerus
- Scapula
What are the different regions of the proximal humerus?
- Head
- Anatomical neck
- Surgical neck
- Greater tubercle
- Inter-tubercular groove
- Lesser tubercle
- Deltoid tuberosity
What is the anatomical neck of the humerus?
The anatomical neck is where the proximal large globular head of the humerus meets the shaft
What is the functional importance of the anatomical neck?
The epiphysis is located here and so this is where growth occurs
What is the surgical neck of the humerus?
The most narrow part of the humerus
What is the clinical relevance of the surgical neck of the humerus?
Stresses are accumulated here when we fall and fractures are likely in this region, hence the name ‘surgical neck’
Which tendon passes through the inter-tubercular groove and where does this tendon insert?
- Biceps long-head tendon
- Inserts onto the glenoid
What is the glenoid?
It is a shallow socket in the shoulder blade
Where does the humeral head rest?
In the glenoid
What is the labrum?
Soft fibro-cartilagenous ring that sits around the glenoid cavity
What is the role of the labrum?
It surrounds the glenoid (socket) and helps to stabilise the joint by deepening the socket
What is the importance of the deltoid tuberosity?
This is where the deltoid muscle inserts
What is sergeant’s stripes loss of sensation?
Surgical neck fracture impacts the axillary nerve which winds around the surgical neck and provides sensation over the shoulder tip (where the sergeant’s stripes would normally be)
- So there is loss of sensation and motor activity to the shoulder tip!
What are the coracoclavicular ligaments?
The trapezoid ligament (lateral)
The conoid ligament
What is the role of the coracoclavicular ligaments?
Connect the scapula to the trunk via the clavicle
Route of the coracoclavicular ligaments?
From the coracoid process to the clavicle
How does the clavicle connect to the acromion of the scapula?
Via the acromioclavicular joint and the coracoacromial ligament
What is the coracoacromial ligament?
The coracoacromial ligament is a strong triangular ligament between the coracoid process and the acromion
What is the function of the coracoacromial ligament?
The function of the coracoclavicular ligament is to allow complex shoulder movement without separation of the scapula from the clavicle
How does the shoulder attach to the body?
Via the clavicle
The humerus attaches to the scapula, but how do the humerus and scapula connect to the main trunk?
Through the acromioclavicular joint and the sternoclavicular joint
What are the most common movements of the shoulder-clavicle motion?
- Around the vertical axis: facing the glenoid anteriorly
2. Around the horizontal axis: facing the glenoid more supero-laterally
What makes the shoulder joint unstable?
The glenoid cavity is very small compared to the area of the humeral head (ball)
- Ball = 4 x socket area
How is the shoulder joint stabilised? Give specific examples
By ligaments which sit over the joint capsule, they deepen and support the joint superiorly, making up for the difference in area between ball and socket
- Glenohumeral ligaments
- Coracohumeral ligament
- Coracoacromial ligament
What is the clinical relevance of the labrum?
We can suffer from labral tears which is often the cause for shoulder dislocations
What are the two different groups of muscles around the shoulder?
- Intrinsic vs extrinsic
- Those which connect the humerus to the scapula and those which connect the scapulo-humeral complex to the trunk
What are the different intrinsic muscles of the shoulder?
- Deltoid
- Teres major
- Rotator cuff (teres minor, subscapularis, supraspinatous & infraspinatous)
What are the extrinsic muscles of the shoulder?
Superficial: trapezius, latissimus dorsi
Deep: levator scapulae, rhomboids
What are the different muscles of the rotator cuff?
- Supraspinatous
- Infraspinatous
- Subscapularis
- Teres minor
Role of the rotator cuff muscles?
Control the position of the head in relation to the glenoid cavity
- Maintain function of the joint during all its movements
Different shoulder movements?
- Flexion
- Extension
- (internal) Medial rotation
- (external) Lateral rotation
- ABduction
- ADDuction
What is a bursa?
Fluid filled bag which allows movement of the muscle and tendon in relative to the bone = MASSIVELY REDUCING FRICTION
Where are bursae found?
Between the supraspinatous muscle, tendon and acromial process (between skin and bone)
Clinical relevance of bursae?
Can become inflamed (SUPRASPINATOUS BURSITIS) making it difficult to abduct the arm = ‘PAINFUL ARC’ of abduction
What is the ‘painful arc’ of abduction? Explain how the arc of pain associates with structures found in the shoulder
When abducting the arm starts at a specific point and ends at a particular angle in the arc
Posteriorly:
- 45-60 degrees = glenohumeral painful arc
- 170-180 degrees = acromioclavicular painful arc
Anteriorly:
- 60-120 degrees = subacromial painful arc
Give another cause of the painful arc of abduction?
Inflammation of the tendon rather than the bursa = SUPRASPINATOUS TENDINITIS
What is shoulder dislocation?
When the humeral head slips out of the glenoid fossa
- When dislocation occurs, the short muscles around the shoulder (teres major, minor and infraspinatus) go into spasm and pull the humeral head medially
