The transverse carpal ligament is a wide ligament that runs across the hand, from the scaphoid bone to the hamate bone and pisiform.
It is the volar ligament that connects the pisiform to the hamate.
Situated beneath the pisiform, it is one of the carpal bones that form the carpal arch, within which lies the carpal tunnel.
The triangular bone may be distinguished by its pyramidal shape, and by an oval isolated facet for articulation with the pisiform bone.
Almost all carpals (except the pisiform) have six surfaces.
The pisiform bone is somewhat unusual, in that it first appears in primitive reptiles, and is never found in amphibians.
In the wrist the pisiform is about as large as the ulnar carpal, not much smaller or absent.
In this context the pisiform is regarded as a sesamoid bone embedded in the tendon of the flexor carpi ulnaris.
