The triangular fibrocartilage complex

The triangular fibrocartilage complex TFCC is formed by:

• Triangular fibrocartilage TFC or articular disc
• Ulnocarpal meniscal homologue
• Dorsal and volar radiocarpal ligaments
• Ulnar collateral ligament
• Sheath of the extensor carpi ulnaris tendon

The disc, along with its dorsal and volar ligaments, arises from the ulnar aspect of the lunate fossa of the radius and inserts at the base of the fovea of the ulnar styloid process. The ulnar collateral ligament also attaches to the fovea and thickens distally to form the vestigial ulnocarpal meniscal homologue. Fibres also run distally from the fovea and the volar radio-ulnar ligaments to the triquetrum and lunate; these are called the ulnotriquetral and ulnolunate ligaments, respectively. The ulnar collateral ligament reaches the base of the fifth metacarpal distally. Dorsally, the subsheath of the extensor carpi ulnaris blends with the triangular fibrocartilage complex at the fovea and helps to suspend the ulnar aspect of the carpus from the dorsal aspect of the ulna. The extensor carpi ulnaris is unique among the compartmentalized extensor tendons of the wrist in that it lies in its own fibro-osseous tunnel, which is not connected to the true extensor retinaculum. The extensor retinaculum does not attach to the distal part of the ulna; rather, it sweeps around the distal part to insert on the volar aspect of the carpus, principally on the pisiform and the triquetrum. Consequently, the extensor retinaculum contributes very little stability to the distal part of the ulna. However, this arrangement allows unrestricted rotation of the radius about the ulna at the distal radio-ulnar joint.

Last updated 16/09/2004