536 



THE NERVOUS SYSTEM. 



The nerves supplying the anterior two-thirds of the tongue are 

 the lingual branch of the fifth pair, and the chorda tympani, while 

 the posterior portion is innervated by the glossopharyngeal. Some 

 authorities regard the glossopharyngeal as the sole gustatory nerve, 

 and attribute to the lingual branch only tactile properties, while 

 others hold that the fifth nerve is the true nerve of taste, and that 

 whatever function the glossopharyngeal seems to have in this re- 



FIG. 313. Papillar surface of the tongue, with the fauces and tonsils: 1, 1, cir- 

 cumvallate papillae, in front of 2, the foramen caecum ; 3, fungiform papillse ; 4, fili- 

 form and conical papillse ; 5, transverse and oblique rugae ; 6, mucous glands at the 

 base of the tongue and in the fauces ; 7, tonsils ; 8, part of the epiglottis ; 9, median 

 glosso-epiglottidean fold (fraenum epiglottidis) (from Sappey). 



spect is derived from the fifth through anastomosis. It must 

 be regarded as an unsettled question. 



The mucous membrane of the tongue is covered with papillae, 

 lingual papilfa, of three varieties circumvallate, conical, and 

 fungiform. 



The circumvallate papillae (Fig. 313), about twelve in number, 

 form the boundary between the anterior two-thirds and the posterior 



