The pisiform bone is a small, pea-shaped bone located in the wrist, specifically in the proximal row of the carpal bones. It is situated on the ulnar side, resting on top of the triquetrum bone. The pisiform serves as an attachment point for ligaments and muscles, particularly the flexor carpi ulnaris. This bone plays a role in wrist movement and stability. It is unique among the carpal bones because it is classified as a sesamoid bone, meaning it develops within a tendon. The pisiform is important for the overall function of the wrist and hand.