DISSECTION OF THE DOG 173 



The fungiform papillce (papillae f ungif ormes) , though less numerous, are 

 distributed over the same area as the filiform papilla 1 , but do not occur among 

 the conical papillae in the most posterior part of the dorsum. They can be 

 distinguished readily by their rounded form and pale colour. 



The vallate papillce (papilla) vallatae) are generally four in number, two on 

 each side of the median sulcus, arranged along a V-shaped line, the point of 

 the V being directed backwards. Their position is about the line of transition 

 of filiform into conical papillae. Each vallate papilla is large, with a slightly 

 constricted base and a flattened crown which reaches somewhat above the 

 general level of the mucous membrane. Around a papilla is a circular fossa with 

 an outer wall, known as the vallum, slightly raised above the surrounding level. 



The foliate papillce (papillae foliatae) are two in number. One occurs on 

 each side immediately in front of the point of attachment of the glosso-palatine 

 arch to the tongue, and has the form of an oval area crossed transversely by 

 six to eight ridge-like elevations. 



The mucous membrane of the tongue is continuous with that lining the 

 interior of the mouth generally. Over the dorsum it is thick, dense, covered 

 with papillae, and firmly adherent to the underlying fibrous and muscular 

 tissue. Beneath the tongue it is much thinner, smooth, and not so adherent 

 to the subjacent tissues. Posteriorly the glosso- epiglottic fold (plica glosso- 

 epiglottica) connects the tongue and epiglottis. On each side of the fold is 

 a depression known as the epiglottic vallecula. 



Musculi lingua. — The muscular tissue of the tongue is divisible into 

 that which belongs to extrinsic muscles and that which is intrinsic to the 

 tongue itself. The extrinsic muscles — stylo-glossal, hyo-glossal, and genio- 

 glossal — were examined earlier in the dissection. The intrinsic muscular 

 fibres are longitudinal, transverse, and vertical in direction. 



In the dog a thin layer of loose connective tissue in the median plane and 

 separating the muscles of the two halves of the organ, is all that represents 

 the lingual septum (septum linguae). 



If the mucous membrane immediately underneath the tip of the tongue 

 be incised longitudinally, an elongated condensation of fibrous tissue, the 

 lyssa, will be disclosed. 



Pharynx. — The pharynx is a muscular and membranous tube succeeding 

 the mouth and reaching from the level of the mandibular articulation to 

 about the joint between the atlas and epistropheus when the head is extended. 

 Functionally the pharynx belongs to the respiratory as well as the digestive 

 system, since through it pass both air and food. Dissection of the wall of the 

 tube reveals three layers, namely, a layer of muscular tissue, an aponeurotic 

 layer, and a lining of mucous membrane. The muscles of the pharynx have 

 already been considered, and it will have been noticed that the majority of 

 them are so disposed as to act as constrictors of the cavity. The aponeurotic 

 layer, the submucous tela, is intimately connected with the muscles, and 



