A Basic study of the deglutition reflex mechanism

Abstract

The purpose of this investigation is to elucidate the morphological and physiological aspects of the deglutition reflex. Two different procedures were used for this study: 1) microscopic and electronmicroscopic observations of the receptors in the human and feline larynges, 2) simultaneous recordings of electromyogram of 8 selected muscles, i. e., the cricothyroid, thyroarytenoid, posterior cricoarytenoid, mylohyoid, geniohyoid, hyopharyngeal, thyropharyngeal and cricopharyngeal muscles, with polygraphic recordings of laryngeal movement and subglottal pressure during deglutition elicited by water pouring into the pharynx of a cat. On the basis of the results, the following conclusions appear to be justified. 1) Free endings were found in the mucosa of the epiglottis in the feline. 2) Free endings and corpuscular endings were observed in the mucosa of the epiglottis in the human. 3) Free endings were observed in the mucosa of the arytenoid region and vocal fold in the human. 4) Electronmicroscopically, the receptor in the human was found to be adjacent to the basal cell layer of the epithelium with a partially uncapusulated portion. 5) The intrinsic and the extrinsic laryngeal muscles are activated with a highly constant pattern in each deglutition. 6) Subglottal pressure rises before laryngeal elevation, temporarily drops during laryngeal ele vation and rises again during downwards movement of the larynx. This pattern is not affected by resection of the unilateral recurrent laryngeal nerve.