What does the shoulder girdle consist of?
The clavicle and the scapula, which connect the arm to the axial skeleton
What are the FOUR joints in the shoulder girdle?
- sternoclavicular joint (joint between sternum and clavicle)
- acromioclavicular joint (joint between the acromion of the scapula and the clavicle)
- scapulothoracic joint (joint between scapula and ribs)
- glenohumeral joint (joint between humerus and scapula)
What sits in the glenoid cavity?
The head of the humerus
What is the long bone called that connects the sternum and the scapula?
Clavicle
What is the groove in the proximal humerus for?
Groove for tendon of long head of biceps
What is the notch in top of the manubrium of the sternum called?
Jugular notch
What sort of joint is the glenohumeral joint?
Ball and socket type synovial joint. It is the most commonly dislocated joint
What is the glenoid labrum?
The border of fibrocartilage that deepens the glenoid cavity which the humerus sits in
Where are the glenohumeral ligaments found?
They join the humerus and the scapula, around the capsule
What do the coracoacromial and coracoclavicular ligaments join?
Scapula and clavicle
What does the glenohumeral ligament join?
The head of the humerus and the scapula
What does the coracohumeral ligament join?
Humerus and coracoid process
What are the four rotator cuff muscles? (SITS)
- Supraspinatus
- Infraspinatus
- Teres minor
- Subscapularis
Which nerves innervate the rotator cuff muscles?
- SUPRASCAPULAR NERVES innervate supraspinatus and infraspinatus
- AXILLARY NERVE innervates teres minor
- UPPER AND LOWER SUBSCAPULAR NERVES innervate subscapularis
What do all of the rotator cuff muscles work together to do?
They stabilise the shoulder joint
What does the supraspinatus muscle do?
It initiates abduction of the shoulder
What do the infraspinatus and teres minor work together to do?
They externally rotate the shoulder
What does the subscapularis do?
It internally rotates the shoulder
What is contained within the 1-1.5cm gap between the acromion and the head of the humerus?
Subacromial bursa, rotator cuff tendons, capsule, long head of biceps
How do the first 90 degrees of abduction of the arm from the shoulder joint occur?
First 90 degrees comes from glenohumeral joint:
- 0-15 degrees is SUPRASPINATUS (using suprascapular nerve)
- 15-90 degrees is DELTOID (using axillary nerve)
How does abduction of the arm occur when over 90 degrees?
This is due to scapulo-thoracic joint through scapula rotation:
- over 90 degrees is UPPER TRAPEZIUS (using serratus anterior)
Which muscles (and nerves) are responsible for adduction of the arm? (3)
- PECTORALIS MAJOR (medial and lateral pectoral nerves)
- LATISSIMUS DORSI (thoracodorsal nerve)
- TERES MAJOR (thoracodorsal nerve)
Which muscles and nerves are responsible for flexion of the arm? (4)
- ANTERIOR FIBRES DELTOID (axillary nerve)
- PECTORALIS MAJOR (medial and lateral pectoral nerves)
- CORACOBRACHIALIS (musc. nerve)
- BICEPS BRACHII (musc. nerve)
Which muscles and nerves are responsible for extension of the arm?
- POSTERIOR FIBRES DELTOID (axillary nerve)
- LATISSIMUS DORSI (thoracodorsal nerve)
- TERES MAJOR (thoracodorsal nerve)
Which muscles are responsible for internal rotation of the arm?
- subscapularis
- teres major
- pectoralis major
- lattisimus dorsi
Which muscle are responsible for external rotation of the arm?
- infraspinatus
- teres major
Give some ‘static’ stabilisers of the glenohumeral joint
- articular congruency
- glenoid labrum
- capsule
- glenohumeral ligaments
- extra-capsular ligaments
- negative intra-articular pressure
Give some examples of dynamic stabilisers of the glenohumeral joint
- rotator cuff muscles
- biceps brachii
- muscles crossing the shoulder
How does a traumatic anterior dislocation of the humerus appear on an X-ray and on surface anatomy?
- X-ray shows head of humerus has moved inferiorly but no bones are broken
- surface anatomy shows prominent “bump” on the shoulder, which is the acromion
What is a posterior dislocation of the humerus?
Head of humerus is extended outwards at posterior part of glenoid cavity. The shoulder would be in fixed internal rotation. This can be caused by electric shock or seizure
True or false - the acromioclavicular joint does not often dislocate?
False - it has six different possible ways of dislocating
What is calcific tendinitis?
A calcium hydroxyapatite deposit above the humerus. It can cause subacromial impingement if too large, and can cause acute calcification tendinitis (this is SEVERE pain over around two days, resolves in 1-2 weeks) if it bursts.
What does an arm with ‘long head of biceps rupture’ look like?
The long head of the biceps has detached, so the muscle bunches forming a bulge above the elbow
What is shoulder impingement syndrome?
Pain and weakness that occurs when the arm is raised, caused by anything that traps the rotator cuff tendon against the bone above it, causing it to scrape
What is a rotator cuff tear?
This occurs when one or more of the tendons of the four rotator cuff muscles of the shoulder are torn.
What is a reverse anatomy shoulder replacement?
This is a method sometimes used to replace an irreparable shoulder joint. It places the ball part of the joint on the shoulder, and the flat part on the humerus, hence the ‘reverse’ part of the name
True or false - acromioclavicular osteoarthritis is always extremely painful?
False - the majority are asymptomatic
What are the symptoms of glenohumeral osteoarthritis?
Progressive pain and stiffness over years, and crepitus
What are the treatments of glenohumeral osteoarthritis?
- analgesia and exercises
- steroid injections
- eventual joint replacement
What is adhesive capsulitis?
Also known as ‘frozen shoulder’, occurs when the shoulder capsule becomes inflamed and stiff. Causes extreme pain and sleep deprivation
Give some treatments of adhesive capsulitis
- distension arthrography
- manipulation under anaesthesia
- surgical release