334 OF DIGESTION AND NUTRITIVE ABSORPTION, 



[Fig. 84. 



A view of -the interior of the Stomach and Duodenum in situ, the inferior portion of each having been 

 removed; 1, 1, the under side of the liver; 2, the gall bladder; 3, 3, the lesser curvature and anterior faces, 

 as seen from below ; 4, the rugae, about the cardiac orifice ; 5, the pyloric orifice ; 6, the rugse, and thickness 

 of this orifice ; 7, 7, the duodenum ; 8, lower end of the right kidney.] 



subjected. The muscular fasciculi composing the human stomach, are so 

 disposed as to shorten its diameter in every direction ; and by the alternate 

 contraction and relaxation of these bands, a great variety of motion is induced 

 in this organ, sometimes transversely, and at other ' times longitudinally. 

 ** These motions," Dr. Beaumont remarks, " not only produce a constant dis- 

 turbance or churning of the contents of the stomach, but they compel them, at 

 the same time, to revolve about the interior from point to point, and from one 

 extremity to the other." In addition to these movements, there is a constant 

 agitation of the stomach, produced by the respiratory muscles. The motions 

 of the stomach itself are not performed on any very exact plan, and are much 

 influenced by the character of the ingesta, the state of the general system, and 

 by other circumstances. The following is the ordinary course, however, of 

 the revolutions of the food. " After passing the oesophageal ring, it moves 

 from right to left, along the small arch ; thence, through the large curvature, 

 from left to right. The bolus, as it enters the cardia, turns to the left, passes 

 the aperture,* descends into the splenic extremity, and follows the great 

 curvature towards the pyloric end. It then returns, in the course of the 

 smaller curvature, makes its appearance again at the aperture in its descent 

 into the great curvature, to perform similar revolutions. These revolutions 

 are completed in from one to three minutes. They are probably induced in a 

 great measure, by the circular or transverse muscles of the stomach. They 

 are slower at first, than after chymification has considerably advanced ;" at 

 which time also there is an increased impulse towards the pylorus. It is 

 probable that, from the very commencement of chymification, until the organ 

 becomes empty, portions of chyme are continually passing into the duodenum ; 

 for the bulk of the alimentary mass progressively diminishes, and this the 

 more rapidly as the process is nearer its completion. 



445. The accelerated expulsion appears to be effected by a peculiar action 

 of the transverse muscles ; and especially of that portion o them, which sur- 

 rounds the stomach at about four inches from its pyloric extremity. This 

 band is so forcibly contracted in the latter part of the digestive process, that it 

 almost separates the two portions of the stomach into a sort of hour-glass form ; 

 and Dr. B. states that when he attempted to introduce a long thermometer 

 tube into the pyloric portion of the stomach, the bulb was at first gently 



* The fistulous orifice in St. Martin's stomach, through which these observations were 

 made. 



