Pisiform bone joint, articulating with the triquetral bone. It is on a plane anterior to the other carpal bones and is spheroidal in form. The pisiform bone has four surfaces: Unlike the other carpal bones, the pisiform is not involved in movement of the wrist. The etymology derives from the Latin "pīsum" which means "pea". All other tetrapods have pisiform, being the most common sesamoid. As compared with apes, which have an elongated Pisiform, humans have a shorter pisiform bone. This is due to the loss of the single growth plate typically found in other mammalian pisiforms. This may be because of
Hamate bone bone has six surfaces: The "hook of hamate" () is found at the proximal, ulnar side of the hamate bone. The hook is a curved, hook-like process that projects 1–2 mm distally and radially. The hook forms the ulnar border of the carpal tunnel, and the radial border for Guyon's canal. Numerous structures attach to it, including ligaments from the pisiform, the transverse carpal ligament, and the tendon of Flexor carpi ulnaris. Its medial surface to the flexor digiti minimi brevis and opponens digiti minimi; its lateral side is grooved for the passage of the flexor tendons into the palm