The Annular Ligament

Abstract

Background Despite documentations of ligamentous structures of the elbow, the anatomy and clinical and functional importance of the annular ligament has not been comprehensively defined in the orthopaedic literature. Hypothesis The annular ligament is an important component of both the proximal radioulnar and humeroradial joints, as well as an important component of the neighboring muscles and ligaments. Study Design Descriptive laboratory study. Materials and Methods To investigate the annular ligament and its relationship with neighboring structures, macroscopic and microscopic dissections were performed on both upper extremities of 30 cadavers (12 female and 18 male) fixed in 10% formaldehyde and on 1 upper extremity of a fresh cadaver (male). Results The distal ulnar insertion of discrete fibers on the supinator crest was defined as the inferior oblique band of the annular ligament, and the proximal insertion of the annular ligament was defined as the superior oblique band of the annular ligament. These patterns were noted in all specimens. It was difficult to distinguish the fibers of the supinator muscle in every specimen because they were intimately fused with the fibers of the annular ligament. Conclusions The superior and inferior oblique bands of the annular ligament attached proximally and distally onto the ulna, thus helping to secure the annular ligament in place.