THE PHARYNX. 



1599 



disposed to be thrown into folds in the lower part. Mucous glands, on the other 

 hand, are numerous in the upper part, scarce below ; they lie partly within the 

 mucosa and partly in the submucous tissue and between the muscular bundles. The 

 character of the pharyngeal epithelium varies in different localities. In the nasal 

 pharynx the stratified ciliated columnar cells of the nasal fossa are continued as the 

 covering of the pharyngeal mucous membrane, while the oro-pharyn.\ is clothed with 

 stratified squamous epithelium continued from the mouth. The last-named type 

 of epithelium likewise covers the greater part of the laryngeal portion. The 

 exact distribution of the two varieties of cells is subject to considerable individual 

 variation. The ciliated columnar type extends laterally to include the openings 

 of the Eustachian tubes, but lower down gives place to the squamous. By no 



Fig. 1354. 



Base of skull Nasal septum 



-rni ' 



Naso-pharyngeal fold i«|! 





Lymphoid tissue -^3 • ', ' jli 



Posterior pillar of fauces 

 Faucial tonsil-. 



Pharyngo-epiglottic fold — i 



Cut edge of pharynx 



Uvula 



Dorsum of tongue 



Glosso-epiglottic fossa 

 Median glosso-epiglottic fold 



Epiglottis, turned back 

 Smus pyriformis 



Posterior surface of larynx 



Pharynx opened from behind ; epiglottis turned back. 



means the entire posterior surface of the soft palate is clothed with ciliated colum- 

 nar cells, since the entire uvula and the edges of the palato-pharyngeal folds are 

 invested with stratified squamous epithelium. The latter also covers the posterior 

 wall of the pharynx and extends above as far as the vault. When covered with 

 ciliated epithelium, the mucous membrane is redder, thicker, and contains more 

 glands, but fewer papillse, than in those parts in which the squamous cells prevail. 

 While containing much lymphoid tissue, fat is limited to a few deeply seated lobules 

 of adipose tissue. 



Lymphoid Structures. — The upper part of the pharynx contains many 

 lymphoid collections which make the surface uneven. They are much less frequent 

 below. The larger and more constant masses are called * ' tonsils. ' ' These include 

 the /aucz'a/ tonsils in the oro-pharynx, between the pillars of the fauces, the pharyn- 



