喉頭防御反射における知覚受容のメカニズム

Abstract

The embryological function of the larynx is to serve as a protective reflex excecutor. Regarding this reflex glottic closure, the ascending input system from the peripheral laryngeal mucosa to the medulla oblongata was quantitatively and qualitatively clarified from functional and anatomical aspects in felines. After tracheostomy and exposure of the larynx, quantitative stimuli were applied to the laryngeal mucosa by a pressure stimulating apparatus. Unit discharge of the superior laryngeal nerve (SLN) was recorded at a presynaptic area close to the synaptic linkage area of the nucleus solitarius by the microelectrode extracellular method. Furthermore, for the purpose of clarifying the laryngeal receptor, micro-frozen sections were stained utilizing an immunohistochemical staining method of protein gene product (PGP 9.5), CGRP and SP. It was found that the afferent nerve fibers of the SLN were concentrated in the interstitial subnucleus (ni) of the nucleus solitarius. Presynaptic nerve fibers responded to chemostimulation such as pure water and/or a pressure stimulus from a limited area of the base of epiglottis, ary-epiglottic folds and arytenoid region. However, the threshold of response to mucosal mechanical stimuli at the true vocal folds was very high. The electrophysiological results reflected the immunohistochemical study. Positive stained nerve fibers were present at the vocal process and arytenoid region reflecting glottic intradermal fine nerve fibers.