[3] The annular ligament is attached by both its ends to the anterior and posterior margins of the radial notch of the ulna, together with which it forms the articular surface that surrounds the head and neck of the radius.

The ligament is strong and well defined, yet its flexibility permits the slightly oval head of the radius to rotate freely during pronation and supination.

Inferiorly, a few fibres attached to the neck of the radius support a fold of the synovial membrane without interfering with the movements at the joint.

[4] The fibrocartilage on the upper part of the ligament is continuous with the hyaline cartilage of the radial notch.

This article incorporates text in the public domain from page 324 of the 20th edition of Gray's Anatomy (1918)