192 



STOMACH DIGESTION. 



facts in regard to the anatomy of the stomach which make it desir- 

 able to reproduce here the outline of that organ as demonstrated by 



the experiments referred to. 

 Fig. 106 represents the stom- 

 ach of the cat, but probably 

 also represents in all im- 

 portant particulars the hu- 

 man stomach as well. 



Coats of the Stomach. 

 The stomach is composed 

 of four coats : Serous, muscu- 

 lar, submucous, and mucous. 

 The serous coat is a reflec- 

 tion of the peritoneum. The 

 submucous coat, which con- 

 tains the nerves and blood- 

 vessels, is of special interest 



FIG. 106. The cardiac portion is all that 

 part to the left, as the stomach lies in the 

 body, of WX. The cardia is at C. The 

 pylorus is at P, and the pyloric portion is 

 the part between P and WX. This has two 

 divisions : the antrum, between P and YZ, 

 and the pre-antral part, between WX and 

 YZ. The lesser curvature is on the top of 

 the outline between C and P, and the 



greater curvature between the same points as giving to the milCOUS COat 

 along the lower border (Amer. Journ. of t m() biHtv and 



Physiology). 



as per- 



mitting it to form folds, 

 called rugce, when the cavity is empty. This structure is in 

 striking contrast with the anatomic structure of the uterus, in 

 which organ, the submucous coat being absent and the mucous 

 lying directly upon the muscular coat, there is a total want 

 of mobility of the membrane. Aside from this fact, neither 

 the serous nor the submucous coat has any special physiologic 

 interest. The muscular coat is composed of three layers : lon- 

 gitudinal, circular, and oblique. The longitudinal layer is made 

 up of fibers continuous with similar fibers of the esophagus, and 

 is most external that is, immediately beneath the peritoneum. 

 These fibers radiate from the esophageal or cardiac orifice, and 

 are especially abundant in the region of the greater and lesser 

 curvatures. They extend to the intestine, where they form a 

 layer of the muscular coat of that organ. The circular layer is 

 situated internal to the longitudinal, and, as the name implies, its 

 fibers encircle the stomach that is, are in general at right angles 

 to the longitudinal axis of the stomach. At the pyloric orifice of 

 the stomach, where the duodenum begins, these circular fibers are 

 aggregated in such number as to receive the name of pyloric 

 muscle or sphincter pyloricus. Their projection into the interior 

 of the organ at this location with its covering of mucous mem- 

 brane constitutes the pyloric valve. The oblique layer is found 

 especially at the cardiac extremity of the stomach. 



The mucous coat, or mucous me'mbrane, is soft and velvety. 

 Near the cardiac orifice the membrane is about 1^- mm. in thick- 

 ness, and near the pylorus 2 mm., while in general between these 

 two points its thickness is about 1 mm. Its surface is composed 



