Radial collateral ligament

At a glance

English

Radial collateral ligament

Latin (TA2)

Ligamentum collaterale radiale cubiti

System

Ligament

Region

Upper limb

Side

Paired, left and right

About the radial collateral ligament

On the outer side of the elbow, a triangular sheet of ligament steadies the joint against forces that would open it laterally. It is known as the radial collateral ligament, the lateral collateral ligament or, in older texts, the external lateral ligament. Its make-up varies so much between people that it is described either as a single ligament with several lower attachments or as a group of separate bands, the lateral collateral ligament complex.

In the complex view there are four parts. The radial collateral ligament proper arises from the lateral epicondyle of the humerus and fans out downwards, under cover of the common extensor tendon, to blend with the annular ligament; it does not attach to the radius itself, so the radius stays free to rotate. Its posterior portion, often impossible to separate near the epicondyle, is the lateral ulnar collateral ligament, which continues behind the radial head to a ridge on the ulna, the supinator crest, sometimes to a small tubercle there. The annular ligament forms the third part, ringing the radial head between the two margins of the radial notch of the ulna. The fourth, the accessory lateral collateral ligament, links the lower edge of the annular ring with the supinator crest.

Together these bands resist varus stress, the force that would bend the forearm inwards at the elbow, and the lateral ulnar collateral ligament in particular stops the ulna and radius rotating away from the humerus. Failure of that band gives posterolateral rotatory instability, in which the elbow slips partly out of joint when the forearm is supinated and loaded.

Lateral ligament injuries follow elbow dislocations and falls on the outstretched hand. The complex is also linked with lateral epicondylitis (tennis elbow), as its origin lies just beneath the extensor tendons, and overly aggressive surgical release for tennis elbow can damage it. Reconstruction usually uses a tendon graft passed through tunnels in the humerus and ulna.

Attachments and function

Attaches from

The lateral epicondyle of the humerus, beneath the common extensor tendon.

Attaches to

The annular ligament of the radius, with posterior fibres (the lateral ulnar collateral ligament) reaching the supinator crest of the ulna.

Function

Resists varus stress at the elbow and, through its ulnar band, prevents posterolateral rotatory displacement, while leaving the radius free to rotate.

Nerve supply

Articular branches of the radial nerve.

Blood supply

The radial recurrent artery and the middle collateral branch of the profunda brachii artery.