Editing Pisiform bone (section)

==Structure==
The pisiform is a sesamoid bone, with no covering membrane of [[periosteum]]. It is the last [[carpal bones|carpal bone]] to [[ossification|ossify]]. The pisiform bone is a small bone found in the proximal row of the wrist ([[Carpal bones|carpus]]). It is situated where the [[ulna]] joins the wrist, within the [[tendon]] of the [[flexor carpi ulnaris muscle]].<ref>Tim D. White, Human Osteology, 2nd edition (San Diego: Academic Press, 2000)</ref>{{rp|199,205}}

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:
# 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 muscle (hand)|abductor digiti quinti]].
# The ''lateral surface'' is rough, and concave.
# The ''medial surface''' is rough and usually convex.