Palmar trapezoideocapitate ligament

At a glance

English

Palmar trapezoideocapitate ligament

Latin (TA2)

Ligamentum trapezoideocapitatum palmare

System

Ligament

Region

Hand

Side

Paired, left and right

About the palmar trapezoideocapitate ligament

The trapezoid is a small, wedge-shaped bone in the distal row of the carpus, set between the trapezium on its radial side and the capitate on its ulnar side. The palmar trapezoideocapitate ligament crosses the front of the joint between the trapezoid and the capitate, passing across from the palmar surface of one bone to the palmar surface of the other. It is one of the palmar intercarpal ligaments of the distal row.

It works with a deeper interosseous ligament between the same two bones and with a dorsal band on the back of the joint. Together these make the trapezoid and capitate, and with them the trapezium and hamate, a rigid transverse row. The trapezoid carries the base of the second metacarpal and the capitate that of the third, and both of these carpometacarpal joints allow almost no movement. This part of the wrist therefore forms the fixed central pillar of the hand, around which the thumb and the ulnar fingers move.

The ligament lies deep in the floor of the carpal tunnel, behind the tendons of the long finger flexors. Because the distal row moves as one unit, it is seldom injured on its own. When the trapezoid or capitate is displaced, it is usually as part of a larger fracture or dislocation of the carpus caused by a heavy blow or crush.

Attachments and function

Attaches from

Palmar surface of the trapezoid.

Attaches to

Palmar surface of the adjacent capitate.

Function

Binds trapezoid and capitate on the palmar side, keeping the distal carpal row rigid.

Nerve supply

Articular twigs from the anterior interosseous nerve and the deep branch of the ulnar nerve, which supply the palmar side of the carpus.

Blood supply

Small branches of the palmar carpal arch, reinforced by recurrent branches from the deep palmar arch.