198 



PHYSIOLOGY FOR BEGINNERS 



corresponding to the dermis. As in the skin, the dermis 

 is raised up into papillae, but the papilla: of the tongue are 

 much larger and the epithelium over them follows their outline, 

 so that they project out on the surface. 



There are three kinds of papillae. Over the front and at 



the sides of the tongue 

 the papillae, closely 

 packed together, are 

 long and slender, and 

 hence are called fili- 

 form papillae. In 

 many animals they are 

 very long and promi- 

 nent, and the roughness 

 they give to the tongue 

 in such animals as the 

 cat and dog assists these 

 animals in taking up 

 their food. Scattered 

 among the filiform pa- 

 pillae are others, broad 

 at their summits but 

 narrow at their bases, 

 called fungiform pa- 

 pillae, because they are 

 somewhat mushroom- 

 shaped. The third kind 

 are much larger papillae, 

 each shaped like a 

 mound with a ditch 

 round it. These are 

 called circumvallate 

 papillae. In man these 

 are found only at the 

 back of the tongue in 

 two rows in the form of 



a V, pointing backwards. On the circumvallate, and on 

 many of the fungiform papillae, the epithelial cells at the 

 sides of the papillae are arranged into special groups called 

 taste buds. Each taste bud consists of a number of epithelial 



FIG. 88. The mouth widely open to show the 



tongue and palate. 



Uv, Uvula; Tn, tonsils; C.(>, circumvallate papilkc; 

 /'./, fungiform papillae, minute filiform papillae 

 scattered between them. 

 On the right side branches of the fifth nerves to 

 the palate, and of the ninth to the tongue are 

 represented. 



