The Hand and Wrist

Abstract

Figures 5.1, 5.2, and 5.3 illustrate the surface anatomy of the proximal wrist. The wrist is composed of the distal radius and ulna, which articulate with each other to form the radioulnar joint. The distal radius also articulates with the scaphoid and lunate bones. The distal ulna articulates with the triangular fibrocartilage complex (TFCC), which functions much like the meniscus of the knee. The TFCC also has ligamentous attachments to the lunate, capitate, and triquetrum. The distal wrist is composed of the eight carpal bones arranged in two rows. The proximal carpals (scaphoid, lunate, triquetrum, and pisiform) are closely approximated to the radius, while the distal carpals (trapezium, trapezoid, capitate, and hamate) are closely associated with the metacarpal bones. When the wrist deviates radially or dorsiflexes, the scaphoid flexes palmarly, which puts it in a precarious position to be injured when a patient falls, particularly when the patient falls on an outstretched hand. Figure 5.4 shows the basic anatomy of the wrist.