carpal

Carpal refers to the carpus, the cluster of eight small bones that form the wrist in humans and many other mammals. The term comes from Latin carpus, meaning wrist. The carpal bones are organized into two rows that connect the forearm to the hand: a proximal row near the radius and ulna, and a distal row closer to the metacarpals.

The proximal row, from the thumb side toward the little finger, consists of the scaphoid, lunate, triquetrum, and pisiform. The distal row, from the thumb side toward the little finger, comprises the trapezium, trapezoid, capitate, and hamate. These bones interact with the distal radius and ulna to form the radiocarpal joint and with each other via the midcarpal joints, enabling wrist movement and stability.

Functionally, the carpal bones provide a stable yet flexible base for hand movements. They participate in flexion and extension, radial and ulnar deviation, and circumduction of the wrist, while also distributing loads between the hand and forearm. They serve as an integral link between the forearm’s bones and the metacarpals.

Clinical aspects include injuries and disorders of the carpal region. Fractures most commonly involve the scaphoid; fractures may threaten blood supply and risk avascular necrosis. Lunate dislocations and other carpal injuries can occur with acute trauma. Carpal tunnel syndrome involves compression of the median nerve within the carpal tunnel formed by the carpal bones and the transverse carpal ligament. Degenerative changes and coalition between carpal bones can also occur.

Imaging typically starts with X-rays; CT helps define fractures, and MRI assesses soft tissues and occult injuries.