REIDER PART 1
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146_Chapter 4_Hand and Wrist

Figurę 4-72. Sensation tcsting. A, Median nerve. B, Ulnar nerve. C, Radial nerve. D, Radial digital nerve of the long finger. E, Testing for loss of sweating.

E

likely to bc injurcd proximal to the wrist. This loss can be investigated by testing for light touch or sharp-dull sensation on the dorsum of the first web space (see Fig. 4-72C).

Laceration of the digital nerves is common. Transection of a digital nerve causes numbness on the same sidc of the finger as the injured nerve. This numbness is best detected by testing two-point discrimination on the appropriatc side of the volar fingertip (see Fig. 4-72D) Nerve laceration can also be detected by testing for loss of sweat by drawing a plastic pen or wooden pencil along the side of the finger with some downward force In the case of a nerve injury, the loss of sweat leads to reduced friction so that the pen glides as if it is on silk or satin. (Fig. 4-72E)

Special Tests

Tests for Nerve Compression Median Nerve

The most common nerve compression syndrome in the hand and wrist, and probably the most common nerve compression syndrome in the human body, is carpal tunnel syndrome, the compression of the median nerve within the carpal tunnel at the wrist. The base and sides of the carpal tunnel are a U-shaped bed of carpal bones; the roof is the transvcrsc carpal ligament, a thickening of the antebrachial fascia that connects the hook of the hamate with the tubercles of the scaphoid and trapezium. Through this tunnel runs the median nerve along with