Laryngeal Reflex Closure in Several Species of Experimental Animals

Nobody can deny that laryngeal reflex closure is one of the inportant functions of the larynx, protecting the lower airway from the intrusion of foreign bodies.Laryngeal reflex produced by stimulating the internal branch of the superior laryngeal nerve (SLN) was electrophysiologically studied in dogs, cats, rabbits and rats. In addition to that, the results were analyzed and discussed mainly from the viewpoint of histological study which was simultaneously carried out in regard to the arrangement of nerve fibers of the recurrent laryngeal nerve (RLN).The conclusions are as follows:1) Reflex response in RLN by stimulation of afferents in SLN was the most easily obtained in the cat.2) The longest latent period was demonstrated in the dog, the second longest in the rabbit, the third in the cat, and the shortest one in the rat, 3) It was the RLN of the cat in which the nerve fibers related to the laryngeal functions were found the richest.4) From the findings mentioned above, it seems likely that the cat is the most suitable for a neurophysiological study.