What is a Lunotriquetral Ligament?

A lunotriquetral ligament is one of several bands of connective tissue that link the lunate and triquetral bones in the human hand. Two of the seven carpal bones clustered in the base of the hand just above the wrist, the lunate and triquetral are adjacent bones found near the ulna bone on the pinky-finger side of the hand. Along with the scaphoid bone, these two bones make up the proximal row of carpal bones, or those that articulate with the forearm bones to form the wrist joint. Between the lunate and the triquetral and running almost perpendicular to the forearm are the lunotriquetral ligaments, which fill the space between the lateral surface of the triquetral, the outermost of the two bones, and the medial surface of the lunate.

Though the lunate and triquetral bones do not actually form a joint with the ulna, the articulations between the bones of the proximal row of carpals help them to function as a unit. The articulating surfaces are smooth and four-sided, and the joint between them, the intercarpal joint, is an arthrodial or plane joint. A synovial joint, this articulation allows for a small degree of sliding movement of the bones past each other.

Holding these intercarpal articulations together are three types of lunotriquetral ligament. Considered to be the strongest of the three, that which connects the lunate and triquetral on their posterior surfaces is the dorsal intercarpal ligament, running between the two bones in a direction almost perpendicular to that of the forearm. A similar ligament is found between the lunate and scaphoid bones as well.

On the anterior side of these bones is the palmar intercarpal ligament, which connects the lunate and triquetral bones on the opposite side of the dorsal ligament, but which runs parallel to that lunotriquetral ligament. Likewise, a palmar ligament is found between the lunate and scaphoid bones. Located deep to the other tendons and ligaments in the area, the palmar is considered the weaker of the two.

Running between the lunate and triquetral bones on their superior surfaces, those nearest the wrist, is a third kind of lunotriquetral ligament. Known as the interosseous intercarpal ligament, it is flush with the uppermost facets of these bones, crossing the gap between the edges most adjacent to the wrist. It also travels perpendicular to the forearm, and as it runs in a direction that is parallel with the hinge of the wrist, this lunotriquetral ligament covers an expanse that directly articulates with the wrist joint.