Glenoid labrum

Glenoid labrum is a fibrocartilaginous structure ring attached around the margin of the glenoid cavity in the shoulder blade. The shoulder joint is considered a 'ball and socket' joint. However, in bony terms the 'socket' (the glenoid fossa of the scapula) is quite shallow and small, covering at most only a third of the 'ball' (the head of the humerus). The glenoid labrum is a fibrocartilaginous rim attached around the margin of the glenoid cavity.

Anatomy

The glenoid labrum is a ring of fibrocartilage (fibrous cartilage) that runs around the cavity in which the head of the humerus fits. This cavity is called the glenoid cavity. The labrum deepens this cavity and effectively increases the surface area of the 'socket' available to the humeral head. The fibres of the labrum are continuous with the fibres of the tendon of the biceps brachii muscle, which attaches to the labrum.

Function

The function of the glenoid labrum is to deepen the glenoid cavity, increasing the stability of the joint. It also serves as an attachment site for several ligaments.

Clinical significance

Injury to the glenoid labrum can occur from acute trauma or repetitive shoulder motion. Examples of traumatic injury include shoulder dislocations, shoulder blows, or falls on an outstretched hand. Athletes who participate in throwing sports have the highest risk of developing labral tears due to repetitive shoulder motion. In addition, the aging process can contribute to degeneration of the labrum, making it more susceptible to injury.

See also

• Shoulder joint
• Glenoid cavity
• Biceps brachii muscle

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