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pisiform bone (os pisiforme)

parent article - wrist or carpus

pisiform

The pisiform bone (os pisiforme) can be distinguished by its small size, and having a single articular facet. It is pea-shaped and is situated anteriorly to the other bones of the wrist. Its dorsal surface presents a smooth, oval facet, for articulation with the triquetral bone. This facet approaches the superior, but not the inferior border of the bone. The palmar (volar) surface is rounded and rough, giving attachment to the transverse carpal ligament, and to the flexor carpi ulnaris and abductor digiti quinti. The lateral and medial surfaces are also rough, the former being concave, the latter usually convex.

Articulation: the pisiform bone articulates only with one other bone, the triquetral.

Volar: Pertaining to both the palm and sole. It comes from word "vola" which the ancient Romans used for "the palm of the hand and the sole of the foot."

cf palmar (palm side of hand)and plantar (sole of foot)

The Triangular Bone (os triquetrum; cuneiform bone)

lentiform bone The etymology derives from the Latin pīsum which means "pea."

By comparison, the term "palm" applies to only the palm (the grasping side) of the hand. The Romans actually used the word "palma" for the outstretched palm of the hand.

In anatomy, a sesamoid bone is a bone embedded within a tendon.

Sesamoid bones are typically found in locations where a tendon passes over a joint, such as the hand, knee, and foot. Functionally, they act to protect the tendon and to increase its mechanical effect. The presence of the sesamoid bone holds the tendon slightly further away from the center of the joint and thus increases its moment arm. The sesamoid prevents the tendon from flattening into the joint as the tendon tension increases and therefore also maintains a more consistent moment arm through a variety of possible tendon loads.