Pisiform

Original Editor - Nina Myburg

Top Contributors - Nina Myburg, Kim Jackson, Nikhil Benhur Abburi, Wendy Snyders and Leana Louw

Description

Pisiform bone (Left Hand)

The pisiform is one of eight carpal bones that forms part of the wrist joint. The name pisiform is derived from the Latin word pisum which means "pea". It can be felt on the anteromedial side of the wrist.  

Structure

It is the smallest carpal bone and is a pea-shaped bone. It is considered a sesamoid bone and contributes to wrist stability. The pisiform can be found in the proximal row of carpal bones.

Function

The pisiform serves as an attachment for tendons and ligaments. The flexor carpi ulnaris covers the volar surface and the other connections onto the pisiform include the pisohamate ligament, extensor retinaculum, origin of the abductor digiti minimi, pisometacarpal ligament and anterior annular ligament.

The pisiform also forms part of the ulnar canal or Guyon canal. The Guyon canal is a fibro-osseous tunnel of which the pisiform forms part of the ulnar border. The ulnar nerve and ulnar artery pass through this canal.

Articulations

The pisiform does not form part of the wrist joint movement, unlike all other carpal bones. It is situated where the ulna and the wrist meet but articulates with the triquetrum only. It lies in a plane anterior and superficially to all other carpal bones. 

Muscle attachments

• Flexor carpi ulnaris – This is an extrinsic muscle that attaches to the pisiform, hook of hamate and 5th metacarpal. It allows wrist flexion and adduction.
• Abductor digiti minimi – This is a hypothenar muscle. It allows abduction of the 5th finger and flexion of its proximal phalanx.

See Also

• Wrist and Hand
• Ulna

Resources

Pisiform bone animation

Pisiform bone (left wrist) animation