1 62 ANATOMY AND PHYSIOLOGY FOR NURSES 



levatores palati and tensor palati muscles; the bolus is 

 grasped by the superior constrictor muscle of the pharynx 

 and rapidly forced into the esophagus. The food is pre- 

 vented from entering the posterior nares by the uvula and 

 the closure of the posterior half-arches ; from entering the 

 larynx by its ascent under the base of the tongue and the 

 closure of the epiglottis. 



In the third stage the longitudinal and circular muscular 

 fibers, contracting from above downward, propel the bolus 

 into the stomach. 



THE ESOPHAGUS AND STOMACH 



The esophagus is a tube extending from the lower 

 end of the pharynx, or cavity of the throat, to the stomach, 

 passing through the diaphragm. It is 9 inches long, and 

 consists of two layers of muscle lined with mucous mem- 

 brane. By contraction of these muscles the food is forced 

 along the tube to the stomach. 



The stomach is situated in the left side of the upper 

 portion of the abdomen. Its left extremity is in contact 

 with the diaphragm, and its right is overlapped by the 

 liver. It has two openings: one connected with the 

 esophagus, called the cardiac orifice; the other connected 

 with the upper portion of the intestine, called the pyloric 

 orifice. 



It is composed of three coats or membranes: the 

 exterior or serous coat invests every part of this important 

 organ ; the middle coat is composed of three layers of mus- 

 cular fibers, one set of which is arranged longitudinally, 

 the other, circularly; the interior coat is called the mucous, 

 and is arranged in rugae or folds. The stomach is provided 

 with numerous small glands that secrete the gastric 

 fluids. 



The Gastric Juice. The gastric juice is of an acid 

 character, and possesses very great solvent powers. The 



