NUTRITIVE FUNCTIONS DIGESTION. 



Fig. 1. 



275 



Half of the lower jaw ; a, the base ; 6, the angle ; c, the ramus ; d, 

 the condjle ; e, the coronaid process ; h, the two incisors or cutting 

 teeth; i, one canine or dog tooth; k, two small molar; I, three large 

 molar or grinding teeth. 



4. The jaws perform an important part, in fitting the food 

 for the stomach. The lower jaw only has motion ; being 

 moved by means of strong muscles, which rise from the tern- 

 pies and upper jaw ; and it not only moves directly upwards 

 and downwards, but sideways, so as to grind the food be- 

 tween the teeth, as grain is ground between two mill-stones. 



5. The tongue is likewise very useful in the process of 

 mastication, as it removes the food from one part of the 

 mouth to another, so as to bring every portion bet \veen the 

 teeth ; and then it forms it into a suitable shape for swal- 

 lowing. The tongue is made up by different muscles, and is 

 supplied by nerves, chiefly from the eleventh pair. 



6. The esophagus or meat-pipe, lies directly behind the 

 wind-pipe, and is about one inch in diameter. It connects 

 what is called the pharynx, with the stomach. All these or- 

 gans are lined by a soft, velvet-like membrane, termed mucous 

 membrane, because it is always covered in health, with a vi- 

 scid fluid, called mucus. 



