Ulnolunate ligament

At a glance

English

Ulnolunate ligament

Latin (TA2)

Ligamentum ulnolunatum

System

Ligament

Region

Hand

Side

Paired, left and right

About the ulnolunate ligament

The ulnolunate ligament is a short, strong member of the palmar ulnocarpal ligament, the set of bands that connect the ulnar end of the forearm to the carpus. The other members are the ulnocapitate, ulnotriquetral and ulnopisiform ligaments. The ulnolunate band lies deep to the ulnocapitate and between its two neighbours, the short radiolunate ligament on its radial side and the ulnotriquetral band on its ulnar side.

It arises from the palmar radioulnar ligament, the front edge of the cartilage-and-ligament complex that caps the head of the ulna, rather than from the ulna itself. Its fibres run vertically downwards to the palmar horn of the lunate. Because it springs from this complex, it moves with the radius when the forearm turns, which lets the carpus stay attached to the ulnar side without restricting rotation.

Together with the short radiolunate ligament it holds the lunate firmly from in front. The lunate is the central bone of the proximal row and the one most commonly dislocated, so this palmar support is important. The ulnolunate band also helps to stop the head of the ulna riding upwards and backwards relative to the carpus.

Within the wrist, this palmar ulnocarpal group ranks with the dorsal and palmar radiocarpal ligaments, the dorsal ulnocarpal band and the two collateral ligaments. Its ulnolunate part is relevant in ulnocarpal impaction, where a relatively long ulna presses on the lunate and the disc complex, causing ulnar-sided wrist pain, and in tears of the articular disc.

Attachments and function

Attaches from

The palmar radioulnar ligament at the front of the articular disc complex.

Attaches to

The palmar horn of the lunate.

Function

Holds the lunate from in front and links the ulnar side of the carpus to the forearm without hindering rotation.