Pisiform bone Pisiform bone The pisiform bone ( or ), also spelled pisiforme (from the Latin "pisifomis", pea-shaped), is a small knobbly, sesamoid bone that is found in the wrist. It forms the ulnar border of the carpal tunnel. The pisiform is a sesamoid bone, with no covering membrane of periosteum. It is the last carpal bone to ossify. 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
Biarticular muscle By contracting isometrically (without changing length), they put the joint into a four-bar linkage, allowing the contraction of muscles at one joint to move the other by a fixed amount. Unlike four-bar linkages in which all elements are bone and angle relationships are fixed by the relative bone lengths, the biarticular muscle can hold the joint at many different lengths, creating a range of four-bar properties as needed. Biarticular muscles can also transfer mechanical power between distal and proximal joints, though the direction and magnitude of this transfer varies with anatomy, muscle activity level, and joint angles. This is a