The Triangular Fibro-Cartilage separates the two joints; it is attached by its apex to the outer surface of the styloid process of the ulna, and by its base to the edge of the inner surface of the lower end of the radius below its articulation with the ulna.

Ligaments

The capsule is very imperfect, consisting of a few transverse fibres which,connect the bones ventrally and dorsally.

The synovial membrane lines the joint and passes over the upper surface of the triangular fibro-cartilage.

The Interosseous Membrane is a strong fibrous membrane stretched between the radius and ulna, and attached to their interosseous borders. Above, it extends to within about an inch of the head of the radius, leaving a gap for the passage of the dorsal interosseous vessels; below, it reaches down to the extremities of the bones. The direction of the fibres is downwards from the radius to the ulna.