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. The glenoid labrum deepens the articular cavity, and protects the edges of the bone.