VESSELS AND NERVES OF THE LARYNX. 45 



arytaenoid ligament is as strongly marked as the downward curving 

 fasciculus of the superior, so that it renders the mucous membrane 

 prominent. It should further be mentioned that the differentiation 

 between the true vocal cords and the thyro-arytsenoid muscle is much 

 better denned in Man than in animals. 



The projecting border of the true vocal cord in Man is 

 invested by a layer of tesselated epithelium, having a thickness 

 of about O'l of a millimeter, which is rather suddenly replaced 

 towards the ventricle of the larynx and the trachea by ordi- 

 nary ciliated epithelium; whilst posteriorly it is continuous 

 with the tesselated epithelium covering the arytseno-epiglotti- 

 dean folds. The pavement epithelium of the vocal cords is 

 indented on its deep surface by large papillae, which have a 

 breadth at their base of 0'03 of a millimeter, and project as 

 much as 0*05 or 0'06 of a millimeter into its substance. 



At the lower part of the glottis, and towards the trachea, 

 both the epithelium and the mucous membrane become attenu- 

 ated. The submucous tissue, on the other hand, increases in 

 thickness on the anterior part of the larynx, in consequence 

 of fibres joining it from the crico-thyroid membrane, and it is 

 proportionately increased as it retreats from the mucous mem- 

 brane under the prismatic belly of the thyro-ary tasnoid muscle. 

 At this part it contains numerous glands in its substance, 

 which have a remarkably flattened arrangement, presenting a 

 large surface in proportion to their depth. About the level of 

 the cricoid cartilage the glands are especially accumulated at 

 the posterior surface of the larynx, where the submucous tissue 

 also undergoes a considerable increase in thickness. 



The vessels of the larynx present no peculiarities ; the 

 larger branches run in close proximity to the cartilaginous 

 framework of the organ, or are deeply situated in the soft 

 parts. The smaller branches extend towards the mucous 

 membrane, and break up within it into a fine plexus. 



Nor do the nerves present any characteristic features beyond 

 the circumstance that they are unusually numerous. Branches 

 of various size may be followed into the mucous membrane, 

 but the precise mode in which they terminate is at present 

 unknown. The muscular branches of the superior and of the 



