The radiocarpal joint is formed by the radius, radioulnar disk, and 3 bones in the proximal carpal row: the scaphoid, lunate, and triquetrum. The proximal joint surface is a single biconcave curvature. It is long and shallow in the frontal plane (side to side) while being shorter and sharper in the frontal plane (anteroposterior). The curvature of the distal joint surface is sharper in both directions. The incongruency thus created in the joint allows for greater range of motion at this joint than if there were greater congruency.
The distal radius is triangular in shape and flares distally. The distal lateral extension of the radius is the radial styloid. The distal articular surface of the radius is composed of two concave facets, one for articulation with the scaphoid and one for the lunate. The medial aspect of the distal radius (ulnar notch) is concave for its articulation with the ulna.
A fibrocartilage disc is present at the distal end of the ulna and lies between the distal ulna and the triquetrum and lunate carpals. The disc is important for proper arthrokinematics of the distal radioulnar joint.
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Carpals | Metacarpals | Phalanges | Arches | Bone and Joint Structure | Help | Hand Kinesiology
Lorie Richards and Janice Loudon, October 1997