Inferior glenohumeral ligament

At a glance

English

Inferior glenohumeral ligament

Latin (TA2)

Ligamentum glenohumerale inferius

System

Ligament

Region

Upper limb

Side

Paired, left and right

About the inferior glenohumeral ligament

The shoulder capsule, between the glenoid of the scapula and the humeral head, is thickened on its front and underside by three glenohumeral ligaments, named upper, middle and lower. They are best seen from inside the joint, by opening the capsule from behind and lifting out the humeral head. Of the three the inferior ligament is the largest and the most important for stability.

It arises from the lower part of the glenoid labrum and the adjoining rim of the glenoid cavity and passes to the underside of the humerus at its anatomical neck. It is usually described as a complex of three parts: a thick anterior band, a thick posterior band and, between them, a looser axillary pouch. With the arm at the side the pouch hangs slack beneath the humeral head like a hammock; as the arm is lifted it tightens and supports the head from below.

The ligament's role depends on arm position. In abduction the middle and inferior ligaments tighten while the superior one slackens, and because the humeral head curves more sharply below than above, abduction stretches the inferior ligament further and presses the joint surfaces into their close-packed position. Abduction is limited when the greater tubercle meets the upper glenoid rim; rotating the humerus laterally swings the tubercle backwards, eases the lower fibres slightly and allows about 90 degrees of movement at the joint, or about 110 degrees if the arm is also brought forwards into the plane of the scapula. Lateral rotation tightens all three ligaments and medial rotation slackens them. In the position of abduction with lateral rotation, the anterior band is the main barrier to forward dislocation, and when the arm is flexed and medially rotated the posterior band takes over.

Most shoulder dislocations are forwards and downwards, and they tear the anterior band and labrum from the glenoid, the Bankart lesion. Less often the ligament is pulled off the humerus instead, a HAGL lesion. Failure to heal leads to recurrent instability, treated by reattaching the labrum and ligament, and capsular shift operations tighten a lax pouch.

Attachments and function

Attaches from

The lower glenoid labrum and the inferior rim of the glenoid cavity.

Attaches to

The underside of the humeral anatomical neck.

Function

The main static stabiliser of the shoulder in abduction, resisting forward, backward and downward displacement of the humeral head.

Nerve supply

Articular branches of the axillary nerve, with contributions from the suprascapular and subscapular nerves.

Blood supply

The anterior and posterior circumflex humeral arteries and the suprascapular artery.