THE ALIMENTARY CANAL 57 



are, on either side, two other glands, the submaxillary and 

 the jiublingual, with ducts opening in the floor of the 

 mouth. 



Below the root of the tongue there is a leaf-like pro- 

 jection, the epiglottis, which juts backward and guards the 

 entrance to the larynx. Through the larynx a way is open 

 to the trachea and the lungs. At this point, therefore, 

 the courses taken by the food and by the breath part com- 

 pany. From here the esophagus extends through the neck 

 and the thorax, lying at first behind the trachea, and lower 

 down passing back of the heart. Perforating the dia- 

 phragm slightly to the left of the midline it opens into the 

 stomach. 



The stomach is the most expanded part of the aliment- 

 ary canal. Its position is higher up than is generally as- 

 sumed, so that it is well within the embrace of the lower 

 ribs on the left side. It has a capacity varying greatly 

 with the degree of its distention and with its variations 

 of tone. After a full meal it may contain more than a 

 quart. The form of the stomach also changes consider- 

 ably from time to time, but we distinguish a large, rounded 

 portion toward the left and a more conical region tapering 

 off toward the right and joining the small intestine. The 

 opening from the esophagus into the stomach is called the 

 cardia, and that from the stomach to the small intestine is 

 the pylorus. The pylorus is a trifle to the right of the mid- 

 line. The upper border from the cardia to the pylorus is 

 the "lesser curvature" of the stomach; a line drawn from 

 the cardia around the convex left-hand side and thence 

 along the lower margin to the pylorus is said to follow the 

 "greater curvature." 



Leading away from the pylorus the small intestine de- 

 scribes a short turn, within which is the pancreas. This 

 first curve is called the duodenum. The remainder of the 

 small intestine is a slender tube almost 20 feet in length, 

 coiled upon itself in a confusing manner. Two divisions 

 are recognized, the jejunum, continuous with the duodenum 

 and the ileum, extending onward to join the large in- 



