Glenoid labrum

The glenoid labrum (glenoid ligament) is a fibrocartilaginous rim 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 socket is deepened by the glenoidal labrum.

The labrum is triangular in section, the base is fixed to the circumference of the cavity, while the free edge is thin and sharp.

It is continuous above with the tendon of the long head of the Biceps brachii, which gives off two fasciculi to blend with the fibrous tissue of the labrum.

Structure

Clinical significance

Injury

Tearing of the labrum can occur from either acute trauma or repetitive shoulder motion such as in the sports of swimming and baseball. Acute trauma may be from dislocation of the shoulder, direct blows to the shoulder, and other accidents of the sort. Tears are classified as either superior or inferior in regards to where the tear is in the glenoid cavity. A SLAP lesion (superior labrum, anterior to posterior) is a tear where the glenoid labrum meets the tendon of the long head of the biceps muscle. Symptoms include increased pain with overhead activity, popping or grinding, loss of strength, and trouble localizing a specific point of pain. Because a SLAP lesion involves the biceps, pain and weakness may also be felt when performing elbow flexion with resistance.