Chap. XL1I.] 333 



CHAPTER XLII. 



THE NASAL MUCOUS MEMBRANE. 



487. THE lower part of the nasal cavity is lined 

 with a mucous membrane, which has no relation to 

 the olfactory nerve, and therefore is not connected 

 with the organ of smell. It is covered with a strati- 

 fied, columnar, ciliated epithelium of exactly the same 

 nature as that of the respiratory passages e.g., the 

 larynx and trachea. Large numbers of mucous secret- 

 ing" goblet-cells are met with in it. Below the epi- 

 thelium is a thick hyaline basement membrane, and 

 underneath this is a mucosa of fibrous tissue, with 

 numerous lymph corpuscles in it. In many places this 

 infiltration with lymph corpuscles amounts to diffuse 

 adenoid tissue, or to perfect lymph follicles. 



488. The mucosa contains in its most superficial 

 layer the network of capillaries, but in the rest it 

 includes a rich and conspicuous plexus of venous 

 vessels. 



In the deeper parts of the mucous membrane 

 i.e., in the submucosa are embedded smaller and 

 larger glands, the ducts of which pass through the 

 mucosa, and open on the free surface. Some of the 

 glands are mucous ; others are serous. In some cases 

 (e.g., guinea-pig) almost all glands are serous, and 

 of exactly the same nature as those of the back of 

 the tongue. In some places the mucous membrane is 

 much thicker than in others, and then it contains 

 larger glands, and between them bundles of non-striped 

 muscular tissue. 



489. In the upper or olfactory region (Fig. 165) 

 of the nasal cavity, the mucous membrane is of a 



