Glenoid labrum

Glenoidal labrum
Lateral view of the shoulder showing the glenoid labrum (marked "glenoid ligament")
Latin	labrum glenoidale
Gray's	subject #83 319

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.

It deepens the articular cavity, and protects the edges of the bone.

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, falling on an outstretched arm, 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 (superior labrum, anterior to posterior) lesion 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.

Morphology

Glenoid labrum. Schematic drawing of the transverse section. Morphologic variants of the glenoid labrum with relative distribution in percentage for the anterior labrum. a: 50%. Triangular with line of increased signal intensity along the hyalin articular cartilage. b: 20%. Rounded. c: 7%. Comma-shaped flattened. d: 3%. Absent. e: 15%. Cleaved. f: 8%. Notched. g: Central increase in signal intensity. h: Linear increase in signal intensity. The posterior labrum generally exhibits a triangular or rounded form.

See also

• Bankart lesion
• Hill-Sachs lesion
• SLAP lesion

External links

• glenoid+labrum at eMedicine Dictionary
• Anatomy at Dartmouth upper%20extremity/arthrogramaxial2

References

This article incorporates text from a public domain edition of Gray's Anatomy.

• [1]
• [2]