Pisiform

Pisiform bone
Left hand anterior view (palmar view). Pisiform bone shown in red.
The left pisiform bone
Details
Origins	ulnar collateral ligament
Articulations	triangular
Identifiers
Latin	Os pisiforme
MeSH	A02.835.232.087.319.150.600
TA	A02.4.08.007
FMA	23718
Anatomical terms of bone []

The pisiform bone (/ˈpaɪsᵻfɔːrm/ or /ˈpɪzᵻfɔːrm/), also spelled pisiforme (from the Latin pisifomis, pea-shaped), is a small knobbly, pea-shaped bone that is found in the wrist. It forms the ulnar border of the carpal tunnel.

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 joint, articulating with the triquetral bone. It is on a plane anterior to the other carpal bones and is spheroidal in form.

The pisiform bone has four surfaces:

Unlike the other carpal bones, the pisiform is not involved in movement of the wrist.

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 due to the loss of the single growth plate typically found in other mammalian pisiforms. 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.