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PRINCIPLES OP VETERINARY SCIENCE 



account of its length in the horse it is practically impossible for 

 the animal to vomit through the mouth. Instead, the material 

 is passed along the posterior surface of the soft palate and finds 

 exit via the nasal cavity and nostrils. This also explains why 

 breathing does not take place through the mouth. 



Saccus ctscus 



{left extremity) 



Pyloric gland region 



Fig. 22. — Frontal section of stomach and first part of duodenum of horse. 

 The marked difference in the mucous lining of the various gland regions is clearly 

 shown. (Sisson, Anatomy of Domestic Animals.) 



The pharynx is an organ common to the digestive and respiratory 

 tracts. It is funnel shaped and is situated as a cross-roads 

 between the nasal chambers and the larynx, and the mouth and 

 the esophagus. Its walls are lined with mucous membrane, 

 outside of which are voluntary muscles. There are seven open- 

 ings in the pharynx — viz. : (1, 2) the posterior nares, which com- 

 municate with the nasal chambers; (3) the mouth orifice; (4) 

 the esophagus; (5) the larynx; (6, 7) the eustachian tubes, which 



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