Conduction of the palmar cutaneous branch of the median nerve.

The palmar cutaneous branch of the median nerve (PCBMN) usually arises about 5.5cm proximal to the radial styloid and innervates skin of the thenar eminence. The nerve may be injured by direct trauma or during surgery at the wrist. The action potential of the nerve was recorded in 50 nerves of 25 normal subjects, by antidromic stimulation of the median nerve 10cm from the surface recording electrode over the midthenar eminence. The mean latency and mean amplitude of the evoked response were 2.6 +/- 0.2msec and 12 +/- 4.6 mu v, respectively. The mean duration of the evoked potential was 1.78msec. The technique is simple and may be useful in evaluating lesions of the PCBMN.