The glenohumeral joint, commonly known as the shoulder joint, is a synovial ball and socket joint and involves the articulation between the glenoid fossa of the scapula (shoulder blade) and the head of the humerus (upper arm bone). The glenoid fossa is shallow and needs a labrum to deepen it and aid stability. With 120 degrees of unassisted flexion, the glenohumeral joint is the most mobile joint in the body. Scapulohumeral rythym helps to achieve further range of movement. The rotator cuff muscles of the shoulder produce a high tensile force, and help to pull the head of the humerus into the glenoid fossa.

The glenohumeral joint has a loose capsule that is lax inferiorly and therefore is at risk of dislocation inferiorly. The long head of the biceps brachii muscle travels inside the capsule to attach to the supraglenoid tubercle of the scapula. Because the tendon is inside the capsule it needs a synovial tendon sheath to minimise friction. A number of bursas exist in the capsule to aid mobility.

The capsule can become inflamed and stiff, with abnormal bands of tissue (adhesions) growing between the joint surfaces, causing pain and restricting movement of the shoulder, a condition known as frozen shoulder or adhesive capsulitis.

External links

• Overview at brown.edu
• Overview at ouhsc.edu
• Diagram at yess.uk.com

Upper limb anatomy | Staw ramienny | Olkanivel | Axelled