TH£ HEAD AND NECK 



12 41 



which lie anterior to, and parallel with, the limbs of the sulcus tenni- 

 nalis. The two rows converge backwards and inwards, and so 

 form a capital V. In the median line, at the point of the V, there 

 is a single circum vallate papilla, behind which is the foramen caecum. 

 The free surface of each papilla is broad and flat, and bears secondary 

 papillae, whilst the deep end is somewhat constricted, and is received 

 into a circular pit of the mucosa. In this manner each papilla is 

 surrounded by a space known as the trench. The outer wall of the 

 trench projects slightly beyond the level of the free surface of the 

 papilla, thus forming a circular elevation around it, called the 

 vallum (rampart). It is from this circumstance that the papillae 



Epithelial 



Covering 



Papilla 



Fig. 506. — The Conicai. (Filiform) Papilla of the Tongue. 



have received the name ' circumvallate.' Their sides, as well as 

 the wall of the vallum, contain the taste-buds. 



The tongue contains a number of acinous glands. Some of them 

 open into the trenches around the circumvallate papillae, where taste- 

 buds are present, and are serous in character, these being known as 

 the glands of Ebner. Others open into the foramen caecum, into the 

 crypts on the posterior third of the dorsum, and along the sides of 

 the organ, these being mucous in character, and being known as 

 the glands of Weber. Beneath the apex of the tongue, on either 

 side of the median line, there is a small group of glands, partly 

 serous and partly mucous. These two groups are known as the 

 glands of Blandin, or of Kuhn. 



