520 TONGUE. PAPILLA. 



marks the middle line of the organ, and divides it into symmetrical 

 halves. 



The Papillae of the tongue are the 



Papillae circumvallatae, 

 Papillae conicae, 

 Papillae filiformes, 

 Papillae fungiformes. 



The Papillae circumvallatae are of large size, and from fifteen to 

 twenty in number. They are situated on the dorsum of the tongue, 

 near its root, and form a row on each side, which meets its fellow 

 at the middle line, like the two branches of the letter A. Each 

 papilla resembles a cone, attached by its apex to the bottom of a cup- 

 shaped depression : hence they are also named papillae calyciformes. 

 This cup-shaped cavity forms a kind of fossa around the papilla, 

 whence their name circumvallatee. At the meeting of the two rows of 

 these papillae upon the middle of the root of the tongue, is a deep 

 mucous follicle called foramen caecum. 



The Papilla conicae and filiformes cover the whole surface of the 

 tongue in front of the circurnvallatae, but are most abundant near its 

 apex. They are conical and filiform in shape, and have their points 

 directed backwards. 



The Papillae fungiformes are irregularly dispersed over the dorsum 

 of the tongue, and are easily recognised among the other papillae by 

 their rounded heads and larger size. A number of these papillae will 

 generally be observed at the tip of the tongue. 



Behind the papillae circumvallatae, at the root of the tongue, are a 

 number of mucous glands, which open upon the surface. They have 

 been improperly described as papillae by some authors. 



Vessels and Nerves. The tongue is abundantly supplied with 

 blood by the lingual arteries. 



The Nerves are three in number, and of large size : The gusta- 

 tory branch of the fifth, which is distributed to the papillae, and is the 

 nerve of common sensation and of taste. The glosso-pharyngeal, which 

 is distributed to the mucous membrane, follicles, and glands of the 

 tongue, is a nerve of sensation and motion ; it also serves to associate 

 the tongue with the pharynx and larynx. Panizza's experiments, 

 tending to prove that this is the true nerve of taste, are rendered 

 questionable by recent observations. The hypoglossal is the motor 

 nerve of the tongue, and is distributed to the muscles. 



The Mucous membrane which invests the tongue, is continuous 

 with the dermis along the margin of the lips. On either side of the 

 fraenum linguae it may be traced through the sublingual ducts into 

 the sublingual glands, and along Wharton's* ducts into the sub- 



* Thomas Wharton, an English physician, devoted considerable attention to 



