<prompt> Pisiform is which type of bone:Pneumatic boneSesamoid boneAccessory boneLong bone  <response>: 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. 