CHAPTER VIII 

 THE MOVEMENTS OF THE STOMACH 



IT will be recalled (Chapter VI) that the stomach consists 

 of a main rounded portion from which a much smaller 

 conical segment extends to the right to join the duodenum 

 at the pylorus. The larger part is called the fundus, the 

 tapering region is the antrum. The muscular coats of the 

 antrum are somewhat thicker than those of the fundus and 

 show an especially conspicuous development of the circu- 

 lar elements. There is no such contrast between the two 

 parts of the human stomach as between the thin-walled 

 crop and massive gizzard of the bird, but there is a faint 

 suggestion of an analogous difference. The fundus is, 

 indeed, primarily a place for the storage of food; the an- 

 trum, while not a crushing mechanism, has distinctly 

 greater motor properties. 



The antrum is considered to be set off from the fun- 

 dus by the so-called transverse band. This is an irritable 

 ring of the circular muscle which is often contracted enough 

 to indent the outline of the stomach at this point, and which 

 may occasionally create a temporary division of the gas- 

 tric cavity into two parts. It has been called the sphinc- 

 ter of the antrum, but it cannot fairly be compared with 

 the cardiac and the pyloric sphincters, since these are 

 habitually closed, while closure at the transverse band is 

 rare. 



Regulation of the Cardiac Sphincter. Food and drink 

 entering the stomach pass the cardiac sphincter. The 

 guardian muscle is, usually more or less contracted. It 

 relaxes upon the arrival of the peristaltic wave in the 

 esophagus. If it is recalled that the peristalsis consists of 

 a wave of inhibition running before a contraction, it is 



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