Palmar carpometacarpal ligaments

At a glance

English

Palmar carpometacarpal ligaments

Latin (TA2)

Ligamenta carpometacarpea palmaria

System

Ligament

Region

Hand

Side

Paired, left and right

About the palmar carpometacarpal ligaments

The palmar carpometacarpal ligaments, also called the volar carpometacarpal ligaments, strengthen the front of the joints between the distal row of carpal bones and the four finger metacarpals. They lie deep in the palm, beneath the long flexor tendons in the carpal tunnel and the deep palmar arch, and are weaker than the dorsal set on the back of the hand. Each runs from the palmar face of a carpal bone to the palmar face of a metacarpal base.

Their layout broadly resembles that of the dorsal ligaments, with one difference at the third metacarpal. The trapezium holds the index metacarpal. The ring and little finger metacarpals are both tied to the hamate, close to its hook. The middle finger metacarpal, at the centre of the hand, receives three bands rather than two: a radial band from the trapezium, which passes in front of the flexor carpi radialis tendon sheath; a middle band arising from the capitate; and an ulnar band coming from the hamate. On the ulnar side the band to the fifth metacarpal continues round the joint into its dorsal partner, forming an incomplete capsule.

Working with the dorsal and interosseous ligaments, these bands hold the index and middle finger metacarpals almost immobile on the carpus, providing the fixed central column of the hand. The joints of the ring and little fingers are freer, which allows the ulnar side of the palm to fold forwards and rotate a little during a power grip or when cupping the hand.

Injuries to these joints are uncommon and usually involve the fourth and fifth metacarpals after a blow with a clenched fist. Because the palmar ligaments are weaker than the dorsal ones, displacement of the metacarpal bases is more often towards the back of the hand.

Attachments and function

Attaches from

The palmar faces of the trapezium, capitate and hamate.

Attaches to

The palmar faces of the bases of the second to fifth metacarpals; the third receives three bands.

Function

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

Nerve supply

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

Blood supply

Branches of the deep palmar arch and palmar carpal arch.