Distinctive regulatory system of blood flow in the orofacial area: blood flow increase mediated by parasympathetic vasodilator fibers

Abstract

Studies of the nervous control of blood flow to the orofacial area have revealed the presence of parasympathetic vasodilator fibers in orofacial tissues, such as epithelial tissues, muscles, and salivary glands. Trigeminal afferent inputs reflexively induce activation of these parasympathetic vasodilator fibers, and lead to rapid and marked increases in blood flow in these tissues. Therefore, parasympathetic vasodilation induced by this trigeminal mediated reflex may be involved in the basic physiological adjustments to the orofacial area, and disturbances in this response may be related to orofacial dysfunctions. This review focuses on: i) the distinctive regulatory system of blood flow, especially parasympathetic vasodilation in the orofacial area; ii) their modulations, and; iii) the involvement of autonomic vasomotor responses in the physiological role of the orofacial functions, and in the etiology of orofacial dysfunctions related to disturbances of the autonomic nervous system.