The motor nerve conduction study is a valuable method in diagnosis neuropathic diseases such as entrapment syndrome and polyneuropathy.

The tarsal tunnel syndrome is not as commonly diagnosed as its counterpart in the hand, carpal tunnel syndrome.

Electrodiagnostic evaluation has shown that reduced amplitude and delayed distal altency of motor evoked potentials of medial and lateral plantar nerve are more sensitive indicators of the presence of tarsal tunnel syndrome.

Although, the electric parameters for medial and lateral plantar nerve have not been specified.

This study has been under taken to determine the values of motor conduction velocities, distal latencies and amplitudes of the evoked action potentials of medial and lateral plantar nerves on 36 healthy Koreans, 22 males and 14 females, ranging in age from 15 to 52 years.

The results were summarized as follows:

1) A total of 60 medial plantar nerves was studied and the mean value of conduction velocity was 49.30±4.79 m/sec, that of its distal latency was 4.21±0.50 msec, and that of amplitude was 7.48±1.85 mV.

2) A total of 60 lateral plantar nerves was studied and the mean value of conduction velocities was 47.19±5.10 m/sec, that of its distal latency was 4.21±0.50 msec, and that of amplitude was 7.48±1.85 mV.

3) There was no significant difference in the conduction velocity between medial plantar nerve and lateral platar nerve.

4) The distal latency and amplitude have been found to be faster and larger in medial plantar nerve than in lateral plantar nerve.

5) No statistical variation was noted with advancing age in distal latency conduction velocity and amplitude.

6) There were no significant different related to the sexes and the dominance of the extremities.