Trapezoideocapitate interosseous ligament

At a glance

English

Trapezoideocapitate interosseous ligament

Latin (TA2)

Ligamentum trapezoideocapitatum interosseum

System

Ligament

Region

Hand

Side

Paired, left and right

About the trapezoideocapitate interosseous ligament

The trapezoideocapitate interosseous ligament lies within the joint between the trapezoid and the capitate, two bones of the distal row of the carpus. It joins the non-articular parts of their facing surfaces and lies deep to the palmar and dorsal ligaments that cover the same joint in front and behind. The trapezoid sits on the radial side of the capitate, and the two are fitted tightly against the bases of the second and third metacarpals.

The bones of the distal row are bound so firmly that they move together as a single unit. Each neighbouring pair is joined by an interosseous ligament. Gaps in the interosseous ligaments of the distal row can let the cavity of the midcarpal joint continue down into the carpometacarpal joints, which matters when contrast or fluid injected into one joint appears in another.

The capitate is the keystone of the carpus. It carries the third metacarpal, and together with the trapezoid and the second metacarpal it forms a fixed central column around which the thumb and the ulnar fingers move. The trapezoideocapitate interosseous ligament keeps this column rigid so that grip forces pass straight through it to the radius. It is torn only in severe injuries that disrupt the distal row.

Attachments and function

Attaches from

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

Attaches to

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

Function

Binds trapezoid to capitate deep in their joint, keeping the central column of the carpus rigid.

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.