Activity evoked in hand muscles by the stretch reflex of m. biceps in man.

Experiments were performed on six volunteers, in order to investigate the effect of the activity of the m. biceps branchii on the median and ulnar nerves. The reflex of the m. biceps brachii was evoked by a sudden stretch and the EMG responses of the m. biceps brachii, m. abductor dig. V. and thenar muscles were recorded. Hand muscles produced early EMG potentials, the latency between them, as well as the onset of the electrical response recorded from the m. biceps brachii, being about the same as the conduction time of nerve excitation from biceps to the hand muscles. The possible mechanisms of the origin of the early EMG activity recorded from the hand muscles are discussed.