ORGANS OF SPECIAL SENSE. 37] 



Arteries of Labyrinth: 



Internal auditory,, from the basilar, divides into vestibular 

 and cochlear branches, which accompany the corresponding 

 nerves ; 



Stylo-mastoid, from the posterior auricular, enters through 

 the stylo-mastoid foramen. 



THE TONGUE.* 



The tongue is the organ of the sense of taste, and lies in 

 the floor of the mouth. It is composed of a mass of muscles, 

 the free surface of which is entirely invested with mucous mem- 

 brane. It consists of three parts : 



Base, or root, attached to the hyoid bone, the epiglottis and 

 the soft palate ; 



Body, the back or dorsum of which is marked by a median 

 line or raphe, terminating behind in a cavity the foramen 

 ccecum; 



Apex, or tip, narrow and pointed, directed forward. 



The mucous membrane resembles skin, consisting of a 

 corium or mucosa, containing numerous papillae, and covered 

 with epithelium. The papilla? are most numerous over the ante- 

 rior two-thirds of the dorsum, and consist of three varieties : 



Circumvallate, or largest, about ten in number, about one- 

 twelfth inch wide, are arranged at the back part of the dorsum 

 like the letter V, with the apex directed backward ; 



Fungiform, or medium, are scattered over the organ, espe- 

 cially at the tips and sides; 



Filiform, conical, or smallest, are distributed over the an- 

 terior two-thirds of the dorsum. 



Mucous and serous glands and simple papillae, such as are 

 found in the skin, are also present. 



Taste bulbs, or taste goblets, minute, flask-shaped bodies, 

 about one three-hundredths of an inch in length, are situated in 

 the circumvallate and fungiform papilla?. 



Arteries, are branches of the lingual, facial, and ascending 

 pharyngeal. 



1. Nerves. Hypoglossal, the principal motor nerve. 



2. Lingual branch of glosso-pharyngcal, the special nerve of 

 taste. 



3. Lingual branch of the trifacial, to sides and anterior 

 part; nerve of common sensation. 



4. Chorda tympani, probably nerve of special sense. 



* Vide Lingual Muscles, page 119. 



