QUESTIONS AND ANSWERS 79 



Describe the appearance of the incisors of the horse at the age of (a) 

 5 years, (b) 10 years. 



(a) In the lower jaw, the nippers are worn more or less com- 

 pletely. The intermediates are on a level with the nippers and 

 their posterior border is level with the anterior. The corners are 

 lower than the intermediates. There is a notch on the posterior which 

 is lower than the anterior border ; sometimes this notch is very deep 

 and extends down on the posterior face of the tooth. The corners 

 are fresh and well grown out. The dental arches form a regular 

 semicircle from above, downward, and from one side to the other. 



(b) In the lower jaw, the nippers are rounded. The central 

 enamel is round and small and very near the posterior border. The 

 intermediates are nearly round, while the corners still remain oval. 

 In profile, the arch of the upper and lower teeth from above, down- 

 ward, becomes more angular. 



Give the dental formula of (a) a six-year-old mare, (b) a seven-year-old 

 cow, (c) a one-year-old dog. 

 At the ages stated, these animals would have all their permanent 

 teeth. 



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What modifications are seen in the upper and lower molars of the horse 

 and how do these modifications affect decay? 

 The inferior molars are somewhat longer and much more flat- 

 tened than the superior. Their enamel is but a single organ and is 

 not divided into internal and external parts as in the superior 

 molars. In the superior, the two central rings of enamel completely 

 enclose the infundibula. This arrangement renders the upper 

 molars slightly more susceptible to decay because there is greater 

 possibility of the enamel being broken and an opening for micro- 

 organisms being produced, resulting in caries. 



Describe the tongue. 



The tongue is a fleshy organ, elongated anteroposteriorly, flat- 

 tened on each side, and fixed to the os hyoides and inferior maxilla 

 by the muscles forming the basis of its structure, or by the membrane 

 covering it. It lies in the intermaxillary space, extending from the 

 back part of the mouth to the incisor teeth, and rests on a kind of 

 wide sling formed by the two mylohyoidean muscles. The anterior 



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