Anatomy and Physiology of the Larynx. 81 



lages ; but it is thickest, most vascular, and loosest, having 

 much connective tissue, on the ary - epiglottic folds, 

 ventricular bands, at the lower part of the epiglottis, and 

 in the ventricles. These parts are, therefore, most liable to 

 inflammation and rapid oedema — a fact to be remembered 

 when considering the surgery and pathology of the organ. 



It should also be noted, that between the mucous 

 membrane and the cartilages is a continuous layer of elastic 

 fibrous tissue, which strengthens the larynx and assists the 

 movements of the different pieces that compose it. 



Nerves. — The nerves supplying the larynx are derived 

 from the tenth cranial or vagus nerve — the pneumo- 

 gastric, nervus vagus, or j^cir vagum — which more especially 

 ministers to the functions of organic life. This arises by a 

 number of rootlets from the sides of the medulla oblongata, 

 in two portions or nerves, one of which passes down each 

 side of the neck, after giving off branches to probably all 

 the muscles of the pharynx and its mucous membrane ; 

 and a branch — the superior laryngeal nerve — that endows 

 the mucous membrane of the under surface of the 

 epiglottis, the glottis, and the greater part of the larynx, 

 with acute sensation, while sending supposed motor fibres 

 to one muscle of that organ, the crico-thyroid. In the 

 furrow on each side of the neck, immediately above the 

 trachea, the nerve accompanies the carotid artery, and 

 passing into the chest, detaches most important branches to 

 the chief viscera in that cavity, as well as to some in the 

 abdomen. 



The branches which require most notice here are those 

 it gives to the larynx. They are the swpe^-'ior laryngeal 

 and the inferior laryngeal nerves. 



Superior Laryngeal Nerves. — There are two of these, 

 one for each side of the larynx. Each is derived from its 

 respective pneumogastric trunk, which it leaves soon after 

 the latter has emerged from the cranium ; it passes to the 

 larynx, where it is distributed, as already mentioned, to the 



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