CLINICAL EXAMINATION OF COMMON ISOLATED PERIPHERAL NERVE DISORDERS: INTRODUCTION
The accompanying illustrations are a guide for examining sensory and selected motor function of certain peripheral nerves: radial (Figure A-1), median (Figure A-2), ulnar (Figure A-3), fibular (peroneal) (Figure A-4), and femoral (Figure A-5). The sensory distribution of the lateral femoral cutaneous and obturator nerves is also shown (Figures A-6 and A-7). It is not intended to illustrate the findings of a lesion at any particular level of the nerves depicted. Sensory deficits may be less extensive than the full sensory field of a nerve because the fields of two nerves overlap, because a distal nerve lesion affects only part of the field, or because different sensory modalities are differentially involved.
Testing the radial nerve. (A) Sensory distribution. The radial nerve supplies the dorsolateral surface of the upper arm, forearm, wrist, and hand; the dorsal surface of the thumb; the dorsal surface of the index and middle fingers above the distal interphalangeal joints; and the lateral half of the dorsal surface of the ring finger above the distal interphalangeal joint. (B) Extensor pollicis longus. The thumb is extended at the interphalangeal joint against resistance. (C) Extensor pollicis brevis. The thumb is extended at the metacarpophalangeal joint against resistance. (D) Extensor digitorum. The fingers are extended at the metacarpophalangeal joints against resistance. (E) Abductor pollicis longus. The thumb is abducted (elevated in a plane at 90 degrees to the palm) at the carpometacarpal joint against resistance. (F) Extensor carpi radialis longus. The wrist is extended toward the radial (thumb) side against resistance.
Testing the median nerve. (A) Sensory distribution. The median nerve supplies the dorsal surface of the index and middle fingers, the lateral half of the dorsal surface of the ring finger, the lateral two-thirds of the palm, the palmar surface of the thumb, index finger, middle fingers, and the lateral half of the palmar surface of the ring finger. (B) Flexor digitorum profundus I and II. The index and middle fingers are flexed at the distal interphalangeal joints against resistance. (C) Abductor pollicis brevis. The thumb is abducted (elevated at 90 degrees to the plane of the palm) at the metacarpophalangeal joints against resistance. (D) Opponens pollicis. The thumb is crossed over the palm to touch the little finger against resistance.
Testing the ulnar nerve. (A) Sensory distribution. The ulnar nerve supplies the dorsal and palmar surfaces of the medial one-third of the hand, the dorsal and palmar surfaces of the little finger, and the dorsal and palmar surfaces of the medial half of the ring finger. (B) Flexor digitorum profundus III and IV. The index and middle fingers are flexed at ...