DIGESTIVE SYSTEM OF THE SHEEP 



407 



The salivary glands resemble those of the ox in general, but the parotid duct 

 crosses the surface of the masseter muscle, and opens opposite the third or fourth 



cheek tooth. x • , .1 t* 



The tonsil is bean-shaped and about half an inch (ca. 12 mm.) m lengtli. It 

 does not project into the fauces. The mucous memljrane of the latter presents two 

 deep and very narrow tonsillar sinuses on either side. 



Fig. 30.3.— Cross-section of Sheep, through Ninth Thor.^cic Vertebra, Anterior View. 

 i, Cardiac orifice; ^, oesophageal groove; 3, rumino-reticular orifice: 4, rumino-reticular fold; 5, dorsal sac 

 of rumen; 6, bodv of ninth thoracic vertebra; 7, vena hemiazygos; 8, aorta; 9. posterior mediastinal lymph 

 gland- 10 70, crura of diaphragm; ii, posterior vena cava; ;2. portal vein; i?./., right lung; L./., left lung; ^. 

 spleen (cut very obUquely); L, liver; R, reticulum (posterior wall). Arrow points to reticulo-omasal orifice. 



The fornix of the pharynx presents a median plicated fold which is a continua- 

 tion of the septum nasi. The pharyngeal orifice of the Eustachian tube has the 

 form of a crescentic slit, placed about on a level with the inferior nasal meatus. 

 There are two large Ij/mph glands and a number of ha^molymph glands above the 



pharvnx. , 



The oesophagus has a lumen of about an inch when moderately distended; 



otherwise it resembles that of the ox. 



