THE BUCCAL CAVITY 



93 



all agree in secreting fluids called digestive fluids. These 

 fluids, owing to the presence of certain chemical com- 

 pounds called ferments, dissolve the nutrients with which 

 they come in contact. Other parts, by rolling about and 

 crushing the foods, cause them to become mixed with 

 these fluids, and thus be more readily dissolved. In gen- 

 eral, then, the functions of 

 the parts or organs of the 

 alimentary tract are to se- 

 crete digestive fluids, or 

 to dissolve nutrients, or to 

 crush and mix the nutri- 

 ents with the fluids. We 

 shall consider each of these 

 actions as they occur in 

 the various parts of the 

 tract. 



Regions of the Alimen- 

 tary Canal. 



The buccal cavity. — (See 

 Fig. 24.) This is the name 

 given to that part of the 

 tract usually called the 

 mouth. It is bounded in 

 front and at the sides by 

 the lips, teeth, and cheeks, 

 below by the tongue, and 

 above by the palate. The 

 bony part of the palate which forms the roof of the 

 mouth and is called the hard palate, is extended back- 

 ward "into a soft part (the soft palate) with a pendant 



Fio. 24 — Relation of the buccal and 

 jjasal cavities to the esophagus ; n, 

 brain cavity ; ?, hard palate ; /, uvula ; 

 g, opening of eustachian tube to ear ; e, 

 epiglottis ; Jc, tongue ; c-, windpipe ; 6, 

 esophagus. 



