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
Skeletal muscle "flexor" and "extensor"; "abductor" and "adductor"; "levator" and "depressor"; "supinator" and "pronator"; "sphincter", "tensor", and "rotator" muscles. A flexor muscle decreases the anterior angle at a joint; an extensor increases the anterior angle at a joint. An abductor moves a bone away from the midline; an adductor moves a bone closer to the midline. A levator raises a structure; a depressor moves a structure down. A supinator turns the palm of the hand up; a pronator turns the palm down. A sphincter decreases the size of an opening; a tensor tenses a body part; a rotator turns a bone around