Trigeminus Reflex in Young Infants

Abstract

A WEAK: electrical stimulus on the receptive field of N. trigeminus (parts II and III) in infants between a few weeks and 12 months old is followed by a discharge in the nerves of the muscles, biceps and triceps brachii, and biceps and quadriceps femori, without any visible movement. The activity of these muscles is synchronized. No reciprocal pattern could be detected. We found two groups of latencies—one with a maximum at 140 msec and a second between 300 and 400 msec (Fig. 1). Stimulation of regions other than that supplied by the trigeminal nerve is without effect, unless the stimulus is very strong—a fact which is in accordance with the work of Hooker¹ on human fœtuses. We suppose that the myographically- tested reactions of muscles of the extremities have nothing to do with the Moro-reflex, or common fright reaction, which is often seen after very strong visual, acoustic or tactile stimulation.