Reevaluation of reflex responses of the human masseter muscle to electrical lip stimulation

We examined the human masseter reflex response to electrical stimulation of lower lip to uncover realistic postsynaptic potentials in the trigeminal motor nucleus. We found that the stimulation generates a long-lasting single or compound inhibitory response that is followed by a late, long-lasting excitation. These findings have important implications on the redrawing of the neuronal pathways of the trigeminal nerve that are frequently used to judge neuromuscular disorders of the trigeminal region.