Glottic Closure Reflex

Abstract

Reflex responses elicited in the adductor branches of the recurrent laryngeal nerve (RLN) by electrical stimulation of various nerves were studied on anesthetized cats in order to elucidate the mechanism of glottic closure reflex. The following results were obtained in this experiment.1. A single pulse stimulation to each of the infraorbital branches of the trigeminal nerve (ION), facial nerve branches distal to the level of the stylomastoid foramen (VII), glossopharyngeal nerve (GPN), superior laryngeal nerve of the vagus nerve (SLN), hypoglossal nerve (XII) and great auricular nerve (GAN) elicited reflex responses in the RLNs bilaterally and that to the accessory nerve branches innervating the trapezius muscle elicited reflex responses in the ipsilateral RLN.2. The frequency-dependent attenuation of reflex responses in the right RLN elicited by repetitive stimulation of those nerves on the right side were also studied and it was found that repetitive stimulation of the SLN produced the least attenuation in RLN responses. On the other hand, the attenuation of RLN responses elicited by repetitive stimulation of the GAN occurred most easily.3. The RLN reflex responses evoked by test stimulation of the right SLN were influenced by conditioning stimulation of each of the ipsilateral ION, VII and GPN, but not by that of XII. Those were facilitative and/or inhibitory influences of conditioning stimulation upon the test reflex responses.These results indicate that the protective laryngeal closure reflex may be evoked by various types of sensory stimuli and be influenced by their subtle interactions.