The wrist

Introduction

The wrist joint is not a single joint but comprised of the articulations between the carpal bones(intercarpal joints) and the articulation with the forearm(radiocarpal joint). Functionally, however, the eight carpal bones are arranged and move as two rows of bones; a proximal row, comprising from lateral to medial: scaphoid, lunate, triquetral and pisiform; and a distal row, again from lateral to medial, formed by the trapezium, trapezoid, capitate and hamate. The two rows articulate with each other at what has become known as the midcarpal joint, a sinuous articular area convex laterally and concave medially. The distal surface of the distal row of bones articulates with the bases of the metacarpals.

Because of the functional interdependence of the wrist and hand, all movements of the hand are accompanied by movements at the radiocarpal and intercarpal joints. The wrist complex is capable of movement in two directions. However, when combined with pronation and supination the hand appears to be connected to the forearm by a ball and socket joint, having great intrinsic stability because of the separation of the three axes about which movement occurs.