REIDER PART 1
20

110 Chafier 4_Hand and Wrist

Figurę 4-14. Swollen basilar joint (arrow).

a number of curves and contours (Fig. 4-16). A longitu-dinal arch begins with a prominence at the base of the hand, curves away from the examiner in the middle of the palm, and then curves back toward the examiner at the distal palm and fingers. This arch is formed by the natural resting tension that exists in the finger flexors when the wrist is extended. A transverse arch, oriented perpcndicular to the longitudinal arch, traverses the hand from one side to the other. The arch is formed by the prominences of the muscles on the ulnar side of the hand (hypothenar) and the thumb side (thenar). Flexing the metacarpophalangeal joints of the fingers and flexing and adducting the thumb accentuates these arches, producing the cupped configuration helpful for swimming or scooping water (Fig. 4-17). A break in either of these arches reflects a serious injury to the hand.

The examiner should carefully notę the normal resting position of the fingers. When the wrist is cxtended, the normal resting tension on the flexor tendons of the fingers causes them to lic in an arcade of flexion, which progresses from slight flexion of the index finger to marked flexion of the little finger (Fig. 4-18). A break in this normal arcade usually signifies a flexor tendon injury or restricted joint motion in the involved finger.

Disruption of the flexor tendons may be due to lac-eration or a closed rupture. The most common example of a closed rupture is avulsion of the flexor digitorum profundus insertion from the base of the distal phalanx of the ring finger. This condition is sometimes called jersey finger becausc it most commonly occurs when the fingers of a football player arc pulled into extension as he attempts to grasp the jersey of an opponent for a tackle. This usually occurs in the ring finger, whosc profundus tendon is tethered to those of the little finger and the long finger. Flexor profundus avulsion causes disruption of the normal resting arcade of the fingers because the DIP joint

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Figurę 4-15. A, B, and C, Radial aspect of the wrist. A, anatomie snuff box; B, extensor pollicis longus; C, cxtcnsor pollicis brcvi$ and abductor pollicis longus.