In the hand, the median nerve supplies the lateral two lumbricals, opponens pollicis, abductor pollicis brevis, and flexor pollicis brevis; the remainder are served by the ulnar nerve.
Wasting of the interossei (prominent guttering of the back of the hand), of the web space between thumb and index finger, and softening and flattening of the hypothenar eminence with sparing of abductor pollicis brevis indicates an ulnar nerve lesion.
Isolated wasting of abductor pollicis brevis indicate median nerve lesion in carpal tunnel syndrome.
Global wasting of hand indicate median and ulnar nerve lesion; probably, with damage to T1 root.
More extensive arm wasting may indicate any of the following: syringomyelia of MND; bilateral, symmetrical wasting indicate peripheral neuropathy.
More detailed information on causes of wasting of the small muscles of the hand is given in the aetiology section.
Last reviewed 01/2018