SHOULDER JOINT
The shoulder joint is a synovial joint of baal and socket type.
Articular surfaces
Shoulder joint is formed by thearticulation of the glenoid cavity of scapula and the head of humerus. Therefore, it is also known as glenohumural articulation .
It is a weak joint because the glenoid cavity is too small and shallow to hold the head of humerus.The head of humurs is four times the size the glenoid cavity.
Stability of the joint
Stability of joint is maintain by following factors
1. The musculotendious cuff of shoulder .
2. The glenoid labrum hels in deepening the glenoid fossa.
3. The coracoacromial arch or secondary socket for the head of humerus.
Ligaments
1 The capsular ligament
2 The glenoid labrum
3 The coracohumeral ligament
4 Transverse humeral ligament
Bursae
1 The infraspinatus bursa
2 The subscapularis bursa
3 The subacromial bursa
Relations
Superiorly : Supraspinatus , deltoid and coracoacromial arch.
Inferiorly : Axillary nerve, long head of tricep brachii.
Anteriorly : Short head of bicep brachii and deltoid.
Posteriorly : Teris minor and deltoid
Nerve supply
1 Axillary nerve
2 Suprascapular nerve
3 Musculocutaneous nerve
Blood supply
1 Anterior circumflex humeral vessel
2 posterior circumflex humeral vessel
3 Suprascapular vessels
4 subscapular vessels.
Movements
1 Flexion and extension
2 Abduction and adduction
3 Medial and lateral relations
4 Circumduction.
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