Hand and Wrist Injuries

Abstract

The wrist is formed by articulation of the radius, ulna, and carpal bones, of which there are eight. The radiocarpal joint is formed by the distal radius, scaphoid, and lunate. The ulna does not articulate with the carpal bones. Instead a fibrocartilage triangle sits between the distal ulna and triquetrum. The scaphoid bone links the proximal carpal bones (lunate, triquetrum) and the distal carpal bones (trapezium, trapezoid, capitate, and hamate). The distal row of carpal bones joins to the metacarpal bones to form the carpometacarpal joint. The hand has five metacarpal bones. From proximal to distal there is a base, shaft, and head of the metacarpal. Moving distally are the five metacarpophalangeal joints. This links the phalanges to the metacarpals. MCP joints can flex, extend, abduct, and adduct. Using a combination of these movements, they can move in restricted circumduction. Strong palmar and collateral ligaments support the joints. Additionally, the deep transverse metacarpal ligaments connect the medial four joints to each other and hold the head of the metacarpal bones together. The hand has 14 phalanges. Each digit contains three phalanges and the thumb contains two. More distally there are the simple hinge joints of the phalanges; the proximal and distal interphalangeal joints. Palmar and collateral ligaments support the joints in flexion and extension. 1.2 Nerves All of the nerves that travel to the hand cross the wrist. Three main nerves begin together at the shoulder: the radial nerve, the median nerve, and the ulnar nerve. These nerves carry signals from the brain to the muscles that move the arm, hand, fingers, and thumb. The radial nerve provides sensory innervation to the dorsum of the hand, thumb, index, middle, and part of the ring finger. The median nerve enters the hand through the carpal tunnel and provides motor and sensory innervation to