MSK 2 and 3 - Anatomy Of Shoulder And Upper Arm Flashcards
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 (lower subscapular nerve)