Conduction velocity along human nociceptive reflex afferent nerve fibres.

The conduction velocity along the nociceptive flexor reflex afferent nerve fibres was investigated in human subjects. The posterior tibal nerve was stimulated at two sites by single painful electrical shocks of 1.0 ms duration and with adequate intensity and the reflex EMG discharges were recorded from the short head of the biceps femoris muscle. The fastest reflex conduction velocity along the posterior tibial nerve between the ankle and the popliteal fossa was about 10-25 m/s. Thus the fastest flexor reflex afferent fibres associated with a painful sensation were thought to be included in the A-delta group of cutaneous afferent nerve fibres.