Trapeziotrapezoidal interosseous ligament

At a glance

English

Trapeziotrapezoidal interosseous ligament

Latin (TA2)

Ligamentum trapeziotrapezoideum interosseum

System

Ligament

Region

Hand

Side

Paired, left and right

About the trapeziotrapezoidal interosseous ligament

The trapezium and trapezoid are the two most radial bones of the distal carpal row. They meet at a small, nearly flat joint, and the trapeziotrapezoidal interosseous ligament runs across this joint deep inside it, joining the rough, non-articular parts of their facing surfaces. Shorter palmar and dorsal intercarpal bands cover the same joint on its front and back.

Each bone of the distal row is bound to its neighbour by a palmar, a dorsal and an interosseous ligament, and this arrangement makes the row a nearly rigid transverse arch. The trapezium carries the saddle-shaped joint for the first metacarpal and the trapezoid the base of the second. Unlike the very mobile thumb carpometacarpal joint just beyond it, the joint between trapezium and trapezoid allows only slight gliding.

By holding the trapezium against the trapezoid, the ligament gives a firm base to the thumb ray, so that the strong forces of pinch and grasp are passed on into the rest of the carpus. The trapezium also forms part of the radial wall of the carpal tunnel and anchors the flexor retinaculum by its tubercle, so stability between these bones helps keep the arch of the tunnel intact. Isolated injury to this ligament is rare.

Attachments and function

Attaches from

Non-articular part of the ulnar surface of the trapezium.

Attaches to

Non-articular part of the facing radial surface of the trapezoid.

Function

Binds trapezium and trapezoid together deep in their joint, allowing only slight gliding and giving the thumb ray a firm base.

Nerve supply

Articular twigs from the anterior and posterior interosseous nerves and the deep branch of the ulnar nerve.

Blood supply

Branches of the palmar and dorsal carpal arches that enter the carpal bones.