PHYSIOLOGY 



While these movements of the pyloric mill are going on, the cardiac portion 

 of the stomach is exercising a steady pressure on its contents in consequence 

 of a tonic contraction of its muscular wall, so that each successive portion of 

 the food mass which is loosened by the digestive action of the gastric juice is 

 forced on into the pyloric mill. As digestion proceeds the opening of the 

 pylorus becomes more frequent. The stomach empties itself more and more, 

 until finally the whole of the viscns has the shape of a curved tube (Fig. 337). 



FIG. 338. Sketch of human stomach, in erect position, shortly after a 



bismuth meal. (HERTZ.) 



F, f undus ; u, umbilicus ; IA, incisura angularis ; PC, pyloric canal ; 

 o, oesophagus. 



At the very end of digestion the pylorus may open to allow the passage even 

 of undigested morsels of food. 



I;- Very similar are the changes in the human stomach, as showp. by Hertz. 

 The term fundus is by him limited to that part of the stomach situated 

 above the cardiac orifice (in the erect position). The body of the stomach 

 is marked off, more or less, by the incisura angularis on the lesser curvature 

 corresponding to what we have called the transverse band. The pyloric 

 portion consists of the pyloric vestibule and the pyloric canal, the latter 

 being a tubular portion about 3-0 cm. in length, especially well marked in 

 infants. When a small quantity of food has been swallowed (in the erect 

 position) its weight is sufficient to overcome the resistance of the contracted 

 gastric wall, and it rapidly passes to the pyloric part. Peristalsis begins 

 almost at once, each constriction starting near the middle of the stomach, 

 and deepening as it slowly progresses towards the pylorus (Fig. 338). About 

 one inch from the pyloric canal it is so marked that part of the pyloric 

 vestibule becomes almost completely separated from the rest of the stomach. 



