Shoulder joint :
Articular surface: head of humerous and glenoid cavity of scapula
Nerve supply: axillary nerve, lateral pectoral nerve
Movement and responsible muscle:
Flexion: pectoralis major, deltois –ant fibres
Extension: deltoid- pos fibers, teres major
Abduction :deltoid – middle fibres
Adduction : pectoralis major, latissimus dorsi
Medial rotation: pectoralis major, deltois –ant fibres , subscapularis
Lateral rotation: infraspinatus
Why it is a weak joint?
ans: it is an unstable joint due to large head of humerous and shallow glenoid fossa
How stability of joint is mainatain?
- Glenoid labrum – a fibrocartilage rim increased the concavity of glenoid cavity
- coracoacromial arch – prevent upward displacement
- Rotator cuff – it is formed by tendon of subscapular, supraspinatus, infraspinatus, teres minor. It prevent lateral displacement
- tendon of long head of biceps brachii- gives superior support
- tendon of long head of triceps brachii- gives inferior support
However, this joint is least supported inferiorly.
Elbow
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