CHAPTER XVI. 



SPECIAL SENSES (Continued.) 



THE SENSE OF TASTE. 



TASTE is an organ of special sense, by which as a medium the 

 individual perceives savory impressions. Its principal uses to the 

 economy are two: First, it acts as a guide to the individual in his 

 choice of food, at the same time rendering its mastication a matter 

 of some pleasure. Secondly, it excites the salivary glands reflexly, so 

 that they pour out their juices into the mouth. 



The organ of taste is seated in the oral cavity and in the mucous 

 membrane of the tongue. Its limits are not well defined. The diffi- 

 culty in their determination depends upon the double fact that these 

 organs of taste are endowed with a very delicate sensibility of a 

 tactile nature, and that the gustatory sensibility and the organ of 

 smell are in very close proximity to one another. For these reasons 

 one may very easily believe that certain regions of his mouth are 

 gustatory, when in reality the substances which have touched them 

 have only produced tactile or olfactory impressions. 



Still it has been shown that the principal regions of the oral 

 mucous membrane designed to perceive taste-impressions are at the 

 base and edges of the tongue. In a secondary degree, also, gustatory 

 impressions are perceived in the anterior surface and edge of the 

 soft palate, and the anterior portion of the tongue. All other por- 

 tions of the mouth are incapable of taste-impressions. 



The Tongue. The principal organ of the sense of taste is un- 

 doubtedly the tongue. Its anatomical structure as a muscular organ 

 has already been described when discussing deglutition and the part 

 it played in the role of that important function. At this time it 

 remains but to review such portions as have a direct bearing upon 

 its role as a gustatory member. 



There are three kinds of papillae in the mucous membrane of 

 the tongue : the circumvallate, fungiform, and filiform. They extend 

 from the tip of the tongue to the foramen caBCum. The papilla? con- 

 sist of elevations, visible to the naked eye and covered with strati- 

 ied, squamous epithelium. The central body of each papilla con- 

 iains connective tissue, blood- and lymph-vessels, and nerves. 



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