VII 



DIGESTION 



pushes the food into the back part of the mouth ; the 

 soft palate rises to close the opening into the nose ; the 

 epiglottis closes the opening into the larynx and tra- 

 chea ; and the muscles of the back part of the mouth 

 contract and push the food into the pharynx. The food 

 is now in the pharynx, and there is but one opening by 

 which it can leave. The mouth, nose, and larynx are 

 all closed. The muscles of the pharynx contract and 



FlG. 44. Food in the pharynx in 

 swallowing (Zuppke). 



food 



FlG. 45. Food in the oesophagus on 

 its way to the stomach (Zuppke). 



crowd the food down into the oesophagus. Sometimes 

 it happens that a particle of food gets into the larynx 

 and trachea, and it is only by violent coughing that it 

 can be expelled. 



The cesopJiagus is a tube about nine inches long, ex- 

 tending from the pharynx to the stomach and is closed 

 except while food is actually passing through it. By 

 the action of its muscular fibers, which we have learned 

 run both longitudinally and circularly, the foods are 



