Trigeminovagal reflex elicited by tactile stimulation in cats.

Abstract

Reflex discharges in the vagal nerve fibers elicited by tactile stimulation of the facial distribution area of the trigeminal nerve have been investigated in the urethane-chloralose anesthetized cat.A brief light mechanical stimulation applied to an appropriate area on the dorsum of nose or to the inner surface of nasal cavity elicited reflex discharges in the superior and inferior laryngeal nerves on both sides, but not in the thoracic vagus. A similar stimulation applied to the area surrounding the nostril sometimes also elicited the reflex discharges.The reflex discharges elicited by stimulation of the nasal skin have been attributed to a transmission of cutaneous distortion to subjacent deeper nasal structures. Therefore, the reflex has been designated as the nasolaryngeal reflex.Electromyographic studies revealed that in the nasolaryngeal reflex motor units of adductor muscles (the cricothyroid, thyreoarytenoid and lateral cricoarytenoid) discharged single spikes following a brief light mechanical stimulation of the nose. A resultant flick closure movement of the vocal cords was observed. Concomitantly, the antagonist muscle, the posterior cricoarytenoid, showed a suppression of spontaneously appearing inspiratory discharges.