Bulbar Pathway for Parasympathetic Reflex Vasodilatation in Orofacial Area

The trigeminal somatic stimulation has been reported to evoke a parasympathetic reflex vasodilatation in the various orofacial areas such as lip, tongue, salivary glands (submandibular and parotid glands) and palate. The vasodilatations in the lip, tongue, and salivary glands occurred predominantly in the ipsilateral side to the stimulation, however, the vasodilatation in the palate was observed in the both (ipsilateral and contralateral) sides. This review is to describe the possible neural network within the brain stem A) of the ipsilateral parasympathetic reflex vasodilatation in the lower lip, and B) of the contralateral reflex vasodilatation in the palate when the central cut end of the lingual nerve was electrically stimulated for the trigeminal somatic stimulation.