DIGESTION. 



163 



striated muscle-fibers, is supplied with a myenteric nerve plexus and resem- 

 bles lower portions of the alimentary canal. It is capable of developing a 

 peristalsis merely in response to the pressure of food within and independent 

 of extrinsic nerves. 



GASTRIC DIGESTION. 



After the food has passed through the esophagus it is received by the 

 stomach, where it is retained for a variable length of time, during which 

 important changes are induced in its physical and chemic composition. 

 The disintegration of the food inaugurated by mastication and insalivation 

 is still further carried on in the stomach by the solvent action of the acid fluid 

 there present, until the entire mass is reduced to a liquid or semi-liquid 

 condition. 



The stomach is the dilated and highly specialized portion of the alimen- 

 tary canal intervening between the esophagus and small intestine. When 



OBLIQUE FIBERS OF 

 MUSCLE COAT 



POSITION 

 FTHE 

 SPHINCTER 

 PYLORI 



POSITION OF THE 

 SPHINCTER CARDIAE 



ESOPHAGO-GASTRIC 

 ORIFICE;THE CARDIA 



FUNDUS 



DUODENUM 



PYLORUS 

 ANTRUM 



SPHINCTER 

 ANTRI PYLORICI 



CIRCULAR FIBERS 



OF 

 MUSCLE COAT 



PREANTRAL OR CARDIAC REGION 



FIG. 71. ANATOMIC FEATURES OF THE STOMACH. 



moderately distended with food, it is somewhat conical or pyriform in shape 

 and slightly curved on itself. It is situated obliquely and in some individuals 

 almost vertically in the upper part of the abdominal cavity, extending from 

 the left hypochondrium to the right of the epigastrium. The dimensions 

 and capacity of the stomach undergo considerable periodic variation accord- 

 ing to the extent to which it is distended by food. In the average condition 

 it measures in its long diameter from 25 to 35 centimeters, in its vertical 

 diameter at the cardia 15 centimeters, in its antero-posterior diameter from 

 ii to 12 centimeters. The capacity of the stomach varies from 1500 to 1700 

 c.c. In the empty condition its walls are contracted. and partly in contact, 

 and the entire organ is drawn up into the upper part of the abdominal cavity. 

 The opening through which the food passes into the stomach is known as 

 the esophago-gastric orifice or the cardia. The opening through which' it 

 passes into the intestine is known as the pylorus, the pyloric or gastro- 

 duodenal orifice. Between these two orifices the stomach along its upper 



