Nerve: Median
Compartments: Thenar and central in the hand; and anterior in the forearm
Skeletal muscles: All muscles in the anterior forearm except for the flexor carpi ulnaris and one-half the flexor digitorium profundus; flexor and abductor pollicis brevis, oponens pollicis, and lumbricals 1-2 in the hand
Cutaneous distribution: Skin along the ventrolateral hand, palmar surfaces of digits 1-3, and the lateral one-half of digit 4. Deficits include the tips of digits 1-4.
Neuromuscular deficit: Weakness when flexing the wrist and abducting the wrist and thumb under resistance. “Ape” hand resulting from impaired flexion of digits 1-3 and opposition of the thumb. Denervation is accompanied by thenar atrophy, extension of digits 1-3, adduction of an extended thumb, and cutaneous impairment along the distribution of the median nerve in the hand.
Differential diagnosis: Lesions occurring below the mid-forearm (e.g., carpel tunnel syndrome) are limited to cutaneous deficits plus dysfunction the intrinsic muscles of the hand (see above). No motor impairment at the wrist.
Median Nerve
