Effects of elbow position on motor conduction velocity of the ulnar nerve.

The purpose of this study was to evaluate the ability of the ulnar nerve motor axons to conduct an evoked action potential at three elbow positions (0 degrees, 90 degrees, and 120 degrees). The latency (from above and below elbow), negative-phase amplitude, and duration of the evoked action potential were used to evaluate the effect of elbow position on 50 normal men. The results indicate that latency of the response, negative-phase amplitude, and duration of the evoked action potential did not vary with the elbow position. Clinical implications for the performance of motor nerve conduction studies for the ulnar nerve are presented. Suggestions for arm position during the motor nerve conduction studies are included.