AK T4 Ligaments Involving the Radius & Ulna

Oblique Cord

A cord of ligamentum tissue at the proximal end of the interosseous ligament. It functions to increase stability between the radius and ulna. It takes form of a of a small flattened band, extending downward and lateral from the lateral aspect of the ulnar tuberosity at the of the coronoid process to the radius just inferior to the radial tuberosity. Its fibers run in the opposite direction to those of the interosseous membrane of the antebrachium.

Triangular Ligament

A fibrocartilage articular disc that binds the distal ends of the ulna and radius together and is the main uniting structure of the joint. The base of the triangular ligament is attached to the medial edge of the ulnar notch of the radius, and its apex is attached to the lateral aspect of the base of the styloid process of the ulna. Therefore it has a broad attachment to the radius but a narrow attachment to the styloid process of the ulna, which serves as the pivot point of the rotary movement of the radius

Inter (L. - between) Osseous (L. - bone) Membrane or Ligament

A ligamentum band that runs between the shafts of the ulna and radius. This membrane, while holding the radius and ulna together, does not impede the movement of the radius over the ulna. It also increases the area of attachment both anteriorly and posteriorly for the numerous muscles originating in the antebrachium and also helps absorb force applied to the area.

Anterior (L - volar) Radioulnar Ligament

A narrow band of fibers extending from the anterior inferior mid aspect of the radius to the anterior inferior mid aspect of the head of the ulna. Stabilizes the anterior inferior aspect of the radioulnar joint.

Posterior (L. - dorsal) Radioulnar Ligament

A narrow band of fibers that extends from the posterior inferior mid aspect of radius to the posterior inferior mid aspect of the ulna. Stabilizes inferior posterior aspect of the radioulnar joint.

Annular Ligament

The annular ligament stabilizes the proximal aspect of the radius as the distal three-fourths of the radius rotates around the ulna during pronation and supination. It holds the radial head in the radial notch of the ulna, yet allows it to rotate freely which allows one to pronate & supinate the hand. The diameter of the annular ligament is less below than above in order to keep the radius from slipping out distally.