Left hand anterior view (palmar view). Pisiform bone shown in red.
The left pisiform bone
|Origins||ulnar collateral ligament|
|Anatomical terms of bone|
The pisiform bone (// or //), also spelled pisiforme (from the Latin pisifomis, pea-shaped), is a small knobbly, pea-shaped sesamoid bone that is found in the wrist. It forms the ulnar border of the carpal tunnel.
The pisiform bone is a small sesamoid bone found in the proximal row of the wrist (carpus). It situated where the ulna joins the wrist, within the tendon of the flexor carpi ulnaris muscle.:199,205
The pisiform bone has four surfaces:
- The dorsal surface is smooth and oval, and articulates with the triquetral: this facet approaches the superior, but not the inferior border of the bone.
- The palmar surface is rounded and rough, and gives attachment to the transverse carpal ligament, the flexor carpi ulnaris and the abductor digiti quinti.
- The lateral and medial surfaces are also rough, the former being concave, the latter usually convex.
The etymology derives from the Latin pīsum which means "pea".
As compared with apes, which have an elongated Pisiform, humans have a shorter pisiform bone. This is likely because of the loss of one of two growth plates. This may be because of evolutionary benefits from having a shorter pisiform bone, including facilitating ulnar deviation of the hand, and preventing hyperextension of the wrist, actions that improve the action of clubbing. 
|Wikimedia Commons has media related to Pisiform bone.|
Pisiform bone (red) forms ulnar border of the carpal tunnel. Left hand. Animation.
- Tim D. White, Human Osteology, 2nd edition (San Diego: Academic Press, 2000)
- Beasley's Surgery of the Hand. Thieme New York. 2003. ISBN 9781282950023.
- Kjosness, Kelsey M.; Hines, Jasmine E.; Lovejoy, C. Owen; Reno, Philip L. (November 2014). "The pisiform growth plate is lost in humans and supports a role for in growth plate formation". Journal of Anatomy 225 (5): 527–538. doi:10.1111/joa.12235.
- Young, Richard W. (January 2003). "Evolution of the human hand: the role of throwing and clubbing". Journal of Anatomy 202 (1): 165–174. doi:10.1046/j.1469-7580.2003.00144.x.
- Cross section image: limbs/hand/hand-fr-1 - Plastination Laboratory at the Medical University of Vienna
- Hand kinesiology at the University of Kansas Medical Center
- Illustration at ntu.edu.tw