DIGESTION. AND ABSORPTION IN THE STOMACH 83 



the hepatic arteries running along it between the two layers of 

 the lesser omentum. The large left hand portion of the stomach 

 cavity is called the fundus or greater pouch. The opposite 

 portion of the cavity is called the lesser pouch or antrumpylori. 

 At one end is the cardiac or esophageal opening, at the other 

 the pyloric. 



Histology. The coats of the stomach walls are four. From 

 without inward these are the (i) peritoneal, or serous, (2) mus- 

 cular, (3) sub-mucous and (4) mucous. 



1. The peritoneal coat covers the whole of the organ except- 

 ing an inconsiderable linear area, where the two layers of the 

 lesser (gastro-hepatic) omentum join it along the lesser curvature, 

 and a similar area along the greater curvature, where the serous 

 coats of the anterior and posterior walls leave the organ to form 

 the great omentum. This coat is simply a fold given off from 

 the peritoneum to envelop the stomach in practically the same 

 manner as the other abdominal viscera. Its structure is that of 

 serous membranes in general. 



2. The muscular coat, varying in thickness from -$ in. over 

 the fundus to ^ in. at the pylorus, is disposed in three layers, 

 (a) external longitudinal, (b) middle circular and (c) internal 

 oblique. The longitudinal fibers are continued from the corre- 

 sponding fibers of the esophagus. They are marked along the 

 lesser curvature, but not very distinct over other parts. The 

 circular fibers are not abundant to the left of the esophageal 

 opening. They progressively increase toward the right, and at 

 the pyloric opening constitute a distinct and powerful muscular 

 ring, the pyloric sphincter, which, projecting into the lumen 

 presents a more or less flat surface on the duodenal side to pre- 

 vent the regurgitation of food. The oblique fibers are supposed 

 to be continuous with the circular fibers of the esophagus. They 

 extend over the greater pouch from a point just to the left of 

 the esophageal opening to a point on the greater curvature, about 

 the junction of the middle and pyloric thirds. Here, at the right 



