THE DIGESTIVE SYSTEM 77 



gland is the largest and is located in front of the wing of the atlas, 

 behind the upright portion of the jaw and below the base of the 

 ear. Its length is about 10 inches and thickness nearly 1 inch. 

 Its secretory duct leads from the anterior lower corner of the 

 gland forward and downward, along the inside of the mandible, 

 then it turns outward, around the inferior margin of the jaw, finds 

 its way across the face, and finally ends by piercing the cheek 

 opposite the third upper cheek tooth. The submaxillary gland 

 lies internal to the parotid in the submaxillary space. It is 

 about 10 inches long and is curved with the concavity forward. 

 The submaxillary duct is formed by the union of small radicles, 

 and runs forward from the concave border along the floor of the 

 mouth. It empties beneath the tongue opposite the canine tooth. 

 This opening is plainly seen in the living animal, and is commonly 

 referred to as the "barb." The sublingual gland is placed be- 

 tween the tongue and the horizontal part of the mandible. In 

 the horse this gland has about thirty sublingual ducts, which 

 open in a row on each side of the floor of the mouth. The func- 

 tion of the salivary glands is to secrete saliva. 



The hard palate is bounded in front and on each side by the 

 teeth, behind it is continuous with the soft palate (see Fig. 20). 

 On its surface is a median groove dividing it into two equal parts. 

 Twenty curved alternating grooves and ridges run across each 

 half; the concavity of these is backward. The ridges aid in 

 retaining the food when it is carried toward the back part of the 

 mouth. They are sometimes called "wrinkles" or "bars." The 

 ox has a dental pad at the anterior end of the hard palate to take 

 the place of the incisor teeth. 



The soft palate is a semimuscular organ suspended like a curtain 

 between the mouth and pharynx. It slopes downward and 

 backward from its junction with the hard palate. It presents 

 two surfaces and four borders, and is 5 or 6 inches long in the 

 horse. The anterior surface is toward the mouth, and the pos- 

 terior toward the pharynx, the anterior wall of which it forms. 

 The lateral borders are attached to the walls of the two cavities 

 which the organ separates. The superior border joins the hard 

 palate, while the inferior is free and in contact with the epiglottis, 

 which may lie either in front of or behind the soft palate. Mucous 

 membrane covers both sides of the organ. During the act of 

 swallowing it is raised to allow the food to pass through. On 



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