180 



PRACTICAL PHYSIOLOGY 



Peristalsis should now be studied in more detail. The waves 

 start about midway along the greater curvature. As they pass 

 slowly towards the pylorus they become steadily deeper, until 

 about one inch from the entrance into the pyloric canal the extreme 

 pyloric end of the stomach is, as a rule, completely separated from 

 the rest of the organ (Fig. 169). The part thus cut off gradually 

 diminishes in size owing to the further passage of the peristaltic 

 wave and the simultaneous contraction of its longitudinal muscle - 

 fibres. Its contents can be seen to pass partly backwards as a 

 reflux stream into the stomach and partly through the narrow 

 pyloric canal into the duodenum. 



Intestines. The first part of the duodenum, the " duodenal cap," 

 can be clearly defined in the erect position. The chyme collects in it 



szr 



FIG. 169. Peristalsis in the stomach. 

 P.O., pyloric canal ; D., dttodenal cap. 



until the next peristaltic wave arrives, and it can then be seen passing 

 very rapidly through the rest of the duodenum into the jejunum. 



A second examination should be made between four and five 

 hours after the opaque meal. The stomach is then generally empty. 

 The shadow of the caecum is seen in the right iliac fossa, and in some 

 individuals a small part of the ascending colon is also visible ; the 

 appendix can be frequently recognised, especially if the clecum and 

 end of the ileum are separated from each other by deep palpation. 

 This examination shows that about four hours are required for the 

 passage of food through the small intestine. A diffuse shadow is 

 generally present at this time in the pelvis. It consists of the 

 terminal coils of the small intestine, the last few inches of which 

 can be recognised as they join the csecum. With a narrow 



