Wrist Anatomy and Vascularity

Abstract

The wrist joint comprises the two forearm bones (radius and ulna) and eight carpal bones (scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, and hamate). The four proximal carpal bones (scaphoid, lunate, triquetrum, and pisiform) comprise the proximal carpal row, and the four distal bones (trapezium, trapezoid, capitate, and hamate) make up the distal carpal row. The wrist joint forms the midcarpal joint between the proximal and distal carpal rows, the radiocarpal joint between the radius and proximal carpal rows, and the distal radioulnar joint between the radius and ulna. The triangular fibrocartilage, radioulnar ligament, meniscus homologue, sheath of the extensor carpi ulnaris tendon, and other tissues present on the ulnar side of the wrist are called the triangular fibrocartilage complex (TFCC). The lunate is considered to be the keystone of the entire carpal bone anatomical structure. It has four articular surfaces: proximal, distal, radial, and ulnar, with the volar and dorsal surfaces being nonarticular and attached to the ligaments. The lunate is the most proximal of the carpal bones and is the most susceptible to direct impact with the radius and, because of its relatively weak ligamentous connections with the other carpal bones, it is thought to be the most commonly dislocated of the carpal bones. In 2007, Lamas et al. injected latex into the brachial arteries of 27 cadaveric upper limbs and investigated the arterial distribution and anastomosis in the lunate. The number of blood vessels in the lunate was greater on the palmar side than on the dorsal side.