Articular capsule of glenohumeral joint

At a glance

English

Articular capsule of glenohumeral joint

Latin (TA2)

Capsula articularis articulatio glenohumeralis

System

Joint

Region

Upper limb

Side

Paired, left and right

About the articular capsule of glenohumeral joint

The articular capsule of the glenohumeral joint encloses the ball-and-socket joint between the humeral head, which is large, and the small, shallow glenoid cavity of the scapula. On the scapula it attaches around the glenoid margin, just beyond the glenoid labrum, and above it encloses the origin of the long head of biceps on the supraglenoid tubercle. On the humerus it attaches to the anatomical neck, except below, where it extends further down the shaft. It bridges the intertubercular groove, and the biceps tendon runs inside it, wrapped in a sleeve of synovial membrane.

The capsule is remarkably lax, especially below, where it hangs in a fold when the arm is at the side. This slack allows the shoulder the widest range of movement of any joint, but makes it the easiest major joint to dislocate. Its front wall is reinforced by the superior, middle and inferior glenohumeral ligaments, and above by the coracohumeral ligament, running from the coracoid process to the tubercles. The transverse humeral ligament spans the groove between the tubercles and holds the biceps tendon in place.

Much of the joint's stability comes not from the capsule itself but from the rotator cuff. The tendons of subscapularis in front and of supraspinatus, infraspinatus and teres minor above and behind fuse with the capsule before inserting on the tubercles, forming a continuous cuff that presses the head into the socket. The underside of the capsule has no such cover. The synovial lining often communicates with the subscapular bursa in front.

Most dislocations are anterior, with the head forced out through the weak lower front of the capsule; the labrum and capsule may be torn from the glenoid in a Bankart lesion. In adhesive capsulitis, or frozen shoulder, the capsule thickens and contracts, and the arm becomes painful and stiff in all directions.

Attachments and function

Formed by

Attached around the margin of the glenoid cavity outside the labrum, and to the supraglenoid tubercle above.

Joins

Attached to the anatomical neck of the humerus, reaching further down the shaft on its inferior side.

Movements

Encloses the shoulder joint and, together with the rotator cuff and glenohumeral ligaments, allows wide movement while helping to keep the humeral ball seated on the glenoid.

Nerve supply

Branches of the suprascapular, axillary and lateral pectoral nerves.

Blood supply

The anterior and posterior circumflex humeral arteries and the suprascapular artery, part of the scapular anastomosis.