The pisiform (lentiform) is one of the eight carpal bones found in the hand. Unlike the other carpal bones it articulates only with the triquetral, and equivalents are not found in many other mammals, suggesting that it is a more developed sesamoid bone. It is situated anterior to the plane of the other carpal bones, articulating with the palmar surface of triquetral.
Dorsal surface of the pisiform. Triangular refers to triquetral.
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The pisiform may be felt at the base of the hypothenar eminence. When the wrist is flexed, flexor carpi ulnaris relaxes allowing the pisiform to be moved side to side. If the subject is thin, it may be seen as a bulge when the wrist is extended.
The pisiform is spherical, with a flat dorsal articular facet for the triquetral.
- The tendon of flexor carpi ulnaris attaches to the palmar surface, continuing distally as the so-called pisometacarpal and pisohamate ligaments, both of which are continuations of the tendon rather than distinct ligaments.
- The pisotriquetral joint.
The pisiform ossifies in the ninth or tenth year in females and the twelfth in males.