Pisiform bone Pisiform bone The pisiform bone ( or ), also spelled pisiforme (from the Latin "pisifomis", pea-shaped), is a small knobbly, sesamoid bone that is found in the wrist. It forms the ulnar border of the carpal tunnel. The pisiform is a sesamoid bone, with no covering membrane of periosteum. It is the last carpal bone to ossify. The pisiform bone is a small bone found in the proximal row of the wrist (carpus). It is situated where the ulna joins the wrist, within the tendon of the flexor carpi ulnaris muscle. It only has one side that acts as a
Trapezium (bone) tubercle found on the anterior surface of the bone. It is where sometimes abductor pollicis brevis muscle attaches. The carpal bones function as a unit to provide a bony superstructure for the hand. The trapezium is the most radial of the bones surrounding the carpal tunnel. It is important in thumb movement. The trapezium is susceptible to arthritis at the joint with the metacarpal bone of the thumb, due to overuse. The etymology derives from the Greek "trapezion" which means "a little table", from "trapeza" meaning "table", itself from "(te)tra-" "four" and "pod-" "foot". The bone was first documented in