A ball and socket joint is an articulation between the rounded head of one bone (ball) and the concavity of another (socket). It is a type of synovial joint. This type of joint is multiaxial: it permits flexion/extension, abduction/adduction, and rotation. The only two ball and socket joints of the body are the hips and the shoulder (glenohumeral). The shallow socket of the glenoid cavity permits a more extensive range of motion in the shoulder; the deeper socket of the acetabulum and the supporting ligaments of the hip constrain the movement of the femur.[1]
Capsule, glenohumeral, coracohumeral and transverse humeral ligaments
abduction: deltoid assisted by the supraspinatus; adduction: short scapular muscles (except supraspinatus) when the deltoid relaxes. Assisted by the pectoralis major and latissimus dorsi; flexion: clavicular head of the pectoralis major and the anterior fibres of the deltoid, assisted by the coracobrachialis and biceps; extension: latissimus dorsi, posterior fibres of the deltoid and the long head of the triceps; rotation: lateral rotation: infraspinatus and teres minor, medial rotation: subscapularis and teres major
suprascapular, subscapular, axillary and lateral pectoral nerves
anterior and posterior humeral circumflex, and subscapular arteries
arm flexion, extension, adduction, abduction, and internal and external rotation
