THE LARYNX. 143 



filaments into which the olfactory nerves divide, and large 

 numbers of small mucous glands. 



The pharynx : The upper portion of the pharynx, which 

 has been already described (page 124), belongs to the respira- 

 tory tract, and is lined with ciliated epithelium, while the 

 lower portion, lined with squamous epithelium, pertains rather 

 to the alimentary canal. 



The Larynx. 



The larynx is a cartilaginous box surmounting the trachea 

 and containing the vocal apparatus. 



Its main cartilages, the thyroid, cricoid, and larger portions 

 of the arytenoids, are of the hyaline variety, tending in old 

 age to become ossified. The other cartilages, those of the epi- 

 glottis, certain processes of the arytenoids, the cornicula 

 laryngis, and cuneiform cartilages (cartilages of Santorini and 

 Wrisberg), are elastic cartilage. 



The ligaments and membranes (thyro-hyoid and crico- 

 thvroid) which complete the framework of the larynx are 

 fibro-elastic structures. 



The interior of the larynx is lined with mucous membrane, 

 consisting of an epithelial layer, tunica propria, and sub- 

 mucous tissue. 



The epithelial lining of the larynx above the ventricles and 

 over the true vocal cords consists of stratified squamous 

 epithelium, continuous with that of the pharynx ; the ventri- 

 cles and the portion of the larynx below the vocal cords are 

 covered with stratified ciliated epithelium, like that of the 

 trachea. 



The tunica propria is a fibrous membrane, containing numer- 

 ous elastic fibres. 



The submucosa consists of areolar tissue, extending down 

 to the periehondrial coverings, and containing the larger 

 blood and lymphatic vessels, small racemose mucous glands, 

 occasional masses of lymphoid tissue, and the intrinsic volun- 

 tary muscles of the larynx. 



The epiglottis contains a basis of elastic cartilage in its 

 centre, covered on each side by submucous areolar tissue and 



