The shoulder is equipped for mobility and gross placement of the arm in space. The elbow is equipped for stability. The wrist, hand, and fingers, the final links in the chain, are perfectly equipped for strength and precision. Injury to this area includes impairment of gross and fine motor movements. The extent of an individual's participation restrictions after injury to these areas depends on the nature of necessary tasks and whether or not the dominant extremity is involved. In football, a hand injury that has little consequence to a lineman could be disabling to a quarterback or wide receiver.
The distal portions of the radius and ulna, eight carpal bones, five metacarpals, and 14 phalanges, form the skeleton of the wrist, hand, and fingers (Fig. 17-1). The distal radius broadens to form a small ulnar notch on its medial surface to accept the ulnar head, and the radial styloid process projects off its anterolateral border. The ulnar head is more circular, with the ulnar styloid process arising from its medial surface.
Bones of the wrist and hand, formed by the radius and ulna, 8 carpals, 5 metacarpals, and 14 phalanges.
Having unusual shapes and irregular surfaces, the carpal bones are aligned in two rows (Fig. 17-2). From the radial to ulnar sides, the proximal row consists of the scaphoid, lunate, triquetrum, and pisiform bones. The distal row is formed by the trapezium, trapezoid, capitate, and hamate bones. In the distal carpal row, the trapezium articulates with the first metacarpal, the trapezoid with the second metacarpal, the capitate with the third metacarpal, and the fourth and fifth metacarpals with the hamate. The pisiform "floats" on the triquetrum, acting as a sesamoid bone to improve the mechanical efficiency of the flexor carpi ulnaris muscle. The scaphoid is the most commonly fractured of the carpals, and the lunate is the most commonly dislocated.
Carpal bones of the hand (palmar view).
Much of the length of the hand is formed by the metacarpals, numbered from I (thumb) to V (little finger). Shaped similarly to long bones, the proximal articulating surfaces are concave to accept the convex surface of the carpals. The distal surfaces are convex to accept the concave surface of the proximal phalanx of each of the fingers. Each finger (except the thumb, which has only a proximal and distal phalanx) has a proximal, middle, and distal phalanx. The proximal aspect of these bones is referred to as the base, and the distal aspect is referred to as the head.
Two small sesamoid bones are located over the palmar aspect of the distal end of the ...