The pisiform 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 of the wrist, resting on top of the triquetrum bone. The pisiform serves as an attachment point for several ligaments and muscles, including the flexor carpi ulnaris, which helps in wrist movement. This bone is unique because it is classified as a sesamoid bone, meaning it develops within a tendon. The pisiform plays a role in improving the mechanical advantage of the flexor carpi ulnaris muscle, contributing to the overall function and stability of the wrist joint.