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 structured to provide strength and precision during function. Injury to this area includes impairment of gross and fine motor movements. The extent of an individual’s disability after injury to these areas depends on the activities involved and whether the injury occurred to the dominant side.
The wrist, hand, and fingers form a functionally. complex region of bones, joints, muscles, and ligaments. During activity, these structures must work in concert, as motion in one segment affects other segments, including the elbow.
Injuries to this region often occur following an acute traumatic event or over time through repetitive cyclical movements. For example, an acute traumatic injury to the wrist, hand, or fingers in a gymnast or quarterback could negatively affect their ability to perform in their sport. For those who perform manual labor work and those who regularly work at a computer, repetitive movements can lead to a progressive decline in their ability to do their work.
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.
Palmar (volar) view of the carpal bones of the right hand.
Much of the length of the hand is formed by the metacarpals, numbered from I (thumb) to ...