Chap, xxiii.] MOUTH, PHARYNX, AND TONGUE. 189 



Saliva, obtained from the mouth contains num- 

 bers of epithelial scales, detached from the surface 

 of the mucous membrane, groups of bacteria and 

 micrococci, and lymph corpuscles. Some of these are 

 in a state of disintegration, while others are swollen 

 up by the water of the saliva. In these there are 

 contained numbers of granules in rapid oscillation, 

 called Brownian molecular movement. 



254. The mucous membrane lining the cavity 

 of the mouth is a thin membrane covered on its free 

 surface with a thick stratified pavement epithelium, 

 the most superficial cells being scales, more or less 

 hornified. 



Underneath the epithelium is a somewhat dense 

 feltwork of fibrous connective tissue, with numerous 

 elastic fibrils in networks. This part is the mucosa, 

 and it projects into the epithelium in the shape of 

 cylindrical or conical papillae. 



According to the thickness of the epithelium, the 

 papillae differ in length. The longest are found where 

 the epithelium is thickest e.g., in the mucosa of the 

 lips, soft palate, and uvula. 



Numerous lymph corpuscles are found in the 

 mucosa of the palate and uvula. Sometimes they 

 amount to diffuse adenoid tissue. The deeper part of 

 the mucous membrane is the submucosa. It is looser in 

 its texture, but it is also composed of fibrous connec- 

 tive tissue with elastic fibrils. The glands are- here 

 embedded ; fat tissue in the shape of groups of fat 

 cells up to continuous lobules of fat cells are here to 

 be met with. The large vascular and nervous trunks 

 pass to and from the submucosa. 



255. Striped muscular tissue is found in the 

 submucosa. Of the lips, soft palate, uvula, and pala- 

 tine arches, it forms a very conspicuous portion 

 e.g., musculus sphincter orbicularis, with its outrunners 

 into the mucous membrane of the lip, the muscles of 



