carpale

The carpals, or carpal bones, are a set of eight small irregular bones that form the wrist (the carpus). They are arranged in two rows, the proximal and the distal row, and together with the adjacent radius and ulna provide the bony framework for the wrist and hand.

The eight bones are divided into two rows. In the proximal row from thumb to little finger are the scaphoid, lunate, triquetrum, and pisiform. In the distal row, from thumb to little finger, are the trapezium, trapezoid, capitate, and hamate. The pisiform is a sesamoid bone embedded within the tendon of the flexor carpi ulnaris.

The carpals articulate with each other and with the radius, ulna, and metacarpals to form several joints. The radiocarpal joint primarily links the distal radius with the proximal carpal row, allowing most wrist movements. The midcarpal joints between the proximal and distal rows contribute to wrist flexibility. The carpal bones also serve as a transition between the forearm and the hand, providing a rigid yet flexible platform for hand movements and load transfer.

Functionally, the carpals enable a wide range of wrist motions, including flexion, extension, and radial and ulnar deviation, while stabilizing the hand on the forearm. They also form part of the carpal tunnel, through which the median nerve and several flexor tendons pass.

Clinical relevance includes common injuries such as scaphoid fractures and given the carpal arrangement, conditions like carpal tunnel syndrome. Variations in bone size or fusion can occur but are typically asymptomatic.