Pisiform

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Description:

This is the smallest of the carpal bones. It forms a single articulation with the triquetral bone. It is typically spheroidal, although it can be quite variable in shape. It sits on a plane palmar to all the other carpal bones. Its dorsal surface forms a flat facet. All the other surfaces are rough with the palmar surface providing attachment for the flexor retinaculum, flexor carpi ulnaris, and abductor digiti minimi. The lateral surface is usually marked by a shallow groove for the ulnar artery. The pisiform bone is palpable as the prominent projection on the palmar surface of the wrist about three centimeters distal to the head of the ulna.