Dorsal carpometacarpal ligaments

At a glance

English

Dorsal carpometacarpal ligaments

Latin (TA2)

Ligamenta carpometacarpea dorsalia

System

Ligament

Region

Hand

Side

Paired, left and right

About the dorsal carpometacarpal ligaments

The dorsal carpometacarpal ligaments lie on the back of the hand, just beyond the wrist, where the distal row of carpal bones meets the bases of the finger metacarpals. They are the strongest and most clearly defined of the ligaments around the carpometacarpal joints of the fingers, stronger than the palmar and interosseous bands. Each is a short, flat fascicle running from the dorsal face of a carpal bone to the dorsal face of a metacarpal base.

The pattern follows the way the bones fit together. The second metacarpal, whose base is notched to receive the trapezoid, takes two fascicles: one from the trapezium and one from the trapezoid. The third is held by one from the trapezoid and one from the capitate. The fourth receives a band from the capitate and another from the hamate. The fifth gets just one, from the hamate, and this band continues round the side of the joint into a matching palmar band, so that together they form a partial capsule. The thumb is not included; its saddle joint with the trapezium has its own loose capsule and ligaments.

These ligaments, with the interosseous ligaments between the bases, lock the second and third metacarpals almost rigidly to the carpus. This fixed central pillar gives the hand a stable base against which the fingers can grip. The fourth and especially the fifth carpometacarpal joints are freer, allowing the ulnar side of the palm to flex and rotate slightly when the hand cups or makes a fist.

Dislocation of these joints is uncommon but tends to involve the fourth and fifth metacarpals, often after a punch with a clenched fist, and may be missed on a single radiograph. A bony lump at the base of the second or third metacarpal, a carpal boss, sometimes forms where these bands attach.

Attachments and function

Attaches from

The dorsal faces of the trapezium, trapezoid, capitate and hamate.

Attaches to

The dorsal faces of the bases of the second to fifth metacarpals.

Function

Bind the finger metacarpals to the distal carpal row, holding the second and third almost rigid and allowing slight movement at the fourth and fifth.

Nerve supply

Articular branches of the posterior interosseous nerve and the deep branch of the ulnar nerve.

Blood supply

Branches of the dorsal carpal arch and dorsal metacarpal arteries.