CHAPTER LIV 



THE MECHANISMS OF DIGESTION (Cont'd) 

 THE MOVEMENTS OF THE STOMACH 



The Character of the Movements 



Even from the earliest days it has been recognized that the stomach 

 performs two important functions: (1) receiving the swallowed food 

 and then discharging it slowly into the intestine, and (2) initiating the 

 chemical processes of digestion. In order to understand the mechanism 

 by which the stomach collects and then discharges the food, it is neces- 

 sary first of all to recall certain anatomical facts concerning the organ, 

 and for this purpose it is most convenient to accept the description 

 given by Cannon, which is illustrated in the accompanying figure. The 

 organ is divided into a cardiac and a pyloric portion by a deep notch in 

 the lesser curvature, called the incisura angularis. The cardiac portion 

 is further subdivided into two by the cardiac orifice. The part which 

 lies, in man, above a line drawn horizontally through the cardia is the 

 fundus. The part lying between the fundus and the incisura angularis 

 is known as the body of the stomach, which, when full, has a tapering 

 shape. The pyloric portion lying on the right of the incisura angularis 

 is further divided into three parts: the pyloric vestibule, the antrum and 

 the pyloric canal, the latter of which lies next the pyloric sphincter and 

 in man measures about 3 cm. in length (see Fig. 154). From a study of 

 its development and structure and from a consideration of its behavior 

 when examined radiographically Cole 30 believes that the ascending or 

 first part of the duodenum virtually belongs to the stomach and should 

 be so considered when the gastric movements are under investigation. 

 Since this portion of the duodenum receives and retains the chyme for a 

 short time after its egress from the stomach and in radiographs appears 

 to surmount the pyloric sphincter, he has termed it the " reservoir cap" 

 or pilleus ventriculi. 



The filled stomach of a person standing erect is so disposed that the 

 greatest curvature forms its lowest point, which may be considerably 

 below the umbilicus. As digestion proceeds and the stomach empties, 

 the greater curvature becomes gradually raised, so that ultimately the 

 pylorus comes to be the most dependent part of the stomach. From 



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