716 PHYSIOLOGY OF DIGESTION AND SECRETION. 



said to be mainly swallowed air. The portion of the duodenum 

 just beyond the pylorus seems to be a speciaHzed part to receive 

 and retain for a time the food as it is discharged from the stomach. 

 It is given the name of duodenal bulb or pyloric cap (Fig. 283a). 



Fig. 2S3o.— The stomach, diKulunal bulb ('<. '/.), and the large intestine. The figures along 

 the large intestine indicate the time after the ingestion of a meal when the food reaches the 

 different parts of the colon. (From Hurst.) 



The Musculature of the Stomach. — The m.usculature of the 

 stomach is usually divided into three layers — a longitudinal, an 

 oblique, and a circular coat. The longitudinal coat is external 

 and is continuous at the cardia with the longitudinal fibers of the 

 esophagus; it spreads out from this point along the length of the 

 stomach, forming a layer of varying thickness; along the curva- 

 tures the layer is stronger than on the front and posterior sur- 

 faces, while at the pyloric end it increases considerably in thick- 

 ness, and passes over the pylorus to be continued directly into the 

 longitudinal coat of the duodenum. The layer of obhque fibers 

 is quite incomplete; it seems to be continuous with the circular 

 fibers of the esophagus, and spreads out from the cardia for a 

 certain distance over the front and posterior surfaces of the fundus 

 of the stomach, but toward the pyloric end disappears, seeming to 

 pass into the circular fibers. The circular coat, which is placed 

 between the two preceding layers, is the thickest and most impor- 

 tant part of the musculature of the stomach. At the fundus the 

 circular bands are thin and somewhat loosely placed, but toward 

 the pyloric end they increase much in thickness, forming a strong, 

 muscular mass, which, as we shall see, plays the most important 

 part in the movements of the stomach. At the pylorus itself a 



