Pisometacarpal ligament
Ligamentum pisometacarpeum
A short palmar band at the ulnar edge of the wrist, linking the pisiform with the base of the little-finger metacarpal.
At a glance
- English
- Pisometacarpal ligament
- Latin (TA2)
- Ligamentum pisometacarpeum
- System
- Ligament
- Region
- Hand
- Side
- Paired, left and right
About the pisometacarpal ligament
At the ulnar border of the palm, the pea-shaped pisiform rests on the front of the triquetrum. It is a sesamoid bone that develops inside the tendon of flexor carpi ulnaris, and the tendon's fibres do not end there. They carry on beyond the pisiform as two cords: the pisohamate ligament, which goes to the hook of the hamate, and the pisometacarpal ligament, which heads distally to the base of the little-finger metacarpal.
Seen this way, the ligament is really the far end of a muscle's insertion. When flexor carpi ulnaris shortens, its pull travels through the pisiform and along these bands to the metacarpus, so the muscle can bend the wrist and tilt the hand towards the ulnar side even though it appears to stop on a small carpal bone. The pisiform works like a spacer that lifts the line of pull away from the joint and improves its leverage.
The ligament is a firm, rounded cord on the palmar surface of the carpus. Its upper fibres merge with the capsule of the small synovial joint between pisiform and triquetrum and help to hold the pisiform in place. Just lateral to it lies the ulnar canal, the tunnel between the pisiform and the hook of the hamate through which the ulnar nerve and artery pass into the hand.
Clinically the neighbourhood matters more than the band itself. A ganglion, a fracture of the hook of the hamate or a swelling in this corner of the wrist can press on the deep branch of the ulnar nerve and weaken the small muscles of the hand. Pain over the pisiform during gripping often comes from wear of the pisotriquetral joint.
Attachments and function
- Attaches from
- The distal aspect of the pisiform bone, prolonging the tendon of flexor carpi ulnaris.
- Attaches to
- The palmar face of the fifth metacarpal at its base.
- Function
- Carries the pull of flexor carpi ulnaris past the pisiform to the metacarpus and steadies the pisiform during wrist flexion and ulnar deviation.
- Nerve supply
- Small articular twigs of the ulnar nerve reach the surrounding capsule.
Anthromica
See the pisometacarpal ligament where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
