Histological Study on the Nerve Distribution in the Larynx in Cat

The r. internus of the n. laryngeus superior comiug into the cat's larynx runs through the canal found in the lateral mid-part of the thyroid cartilage and then divides into the ascending and the descending rami, the latter forming the r. communicans communicating with the n. laryngeus inferior and the former, the thicker of the two rami, parting into bundles of varying sizes which run upwards mostly toward the laryngeal side of the epiglottis and partly to the posterior portion of the plica vocalis, whence some finer branches are sent out to the upper portion of the cavum laryngis inferior. These nerve fibres comprise fine vegetative fibres as well as thick sensory fibres and contain large and small ganglia of sympathetic nature in their courses. The sensory fibres contained in the r. communicans finally spread out in the mucous membrane of the cavum laryngis inferior. The n. laryngeus inferior also consists of fine vegetative fibres and thick medullated fibres and accompanying small ganglia in their upward courses passing between the thyroid cartilage and the m. cricothyreoideus, sends out many branches into the laryngeal muscles and besides also a few fine branches composed of vegetative and sensory fibres into the mucous membrane in the lower part of the cavum laryngis inferior. In the laryngeal side of the epiglottis the submucosal and the proprial plexus are very well developed and consequently, this part is best supplied with sensory fibres of all the parts of the laryngeal cavity. Their terminations, however, are somewhat simpler than the same in dog and goat, consisting only of simple branched terminations originated in medium-sized fibres. These terminations, unlike those in man and some animals, rarely end subepithelially, their terminal fibres usually ending in intraepithelial fibres. These terminal fibres are rarely formed of thick fibres as in dog and goat but are usually very fine fibres provided with small knobs, mostly ending sharply or in small knobs in the snperficial layer of the epithelium. The area the second richest in sensory fibres next to the epiglottis is the part of the mucous membrane covering the apex of the arytenoid cartilage behind the plica vocalis. In the mucous membrane of the ventriculus laryngis are found 2 or 3 papillae resembling the taste-budded papillae on the tongue and many sensory fibres run into these papillae too. The thin mucous membrane covering the arytenoid cartilage extending downwards from the rima glott