280 THE MOVEMENTS OF THE STOMACH. 



THE MOVEMENTS OF THE STOMACH. VOMITING. 



Three methods are employed for determining the position of the stomach: 

 (a) the introduction of a rubber bougie through the esophagus, whose passage along 

 the greater curvature of the stomach can be palpated; (6) electric transillumina- 

 tion of the stomach by means of a small round incandescent light attached to 

 the extremity of a stomach-tube. The stomach is previously suitably dilated 

 by the development of carbon dioxid from sodium bicarbonate administered; 

 the interpretation requires great care ; (c) the Rontgen rays have also been em- 

 ployed after filling the stomach with meat mixed with bismuth subnitrate, the 

 latter being impervious to the x-rays. 



For registering the gastric ^ movements, a _ rubber bulb, introduced through 

 an external gastric fistula in animals, and applied in various situations in the in- 

 terior of the stomach, is employed. The bulb is connected with a writing-ap- 

 paratus by means of a column of air. Einhorn has used the gastrograph in 

 human beings. This consists of a metallic capsule attached to the extremity of 

 a rubber tube, which is swallowed. With every movement of the stomach 

 the metallic parts in the interior of the capsule are brought into contact, and thus 

 employed to effect an electrical registration. A series of photographs taken with 

 Rontgen rays also affords information as to the course of the movements and 

 the evacuation of the gastric contents. 



The anterior surface of the empty stomach lies in a frontal position, with a 

 slight tendency to the right and upward, while the posterior surface accordingly 

 occupies the opposite position. When the stomach is moderately distended, the 

 anterior surf ace . rises about the lesser curvature as an axis, so that it forms an 

 angle of from 45 to 48 with the horizon. When the distention is more marked, 

 the stomach comes progressively to occupy more nearly the horizontal position, 

 so that its anterior surface gradually becomes the superior surface. 



The muscular coat of the stomach consists of an external or longitudinal layer 

 of fibers, a middle or circular layer, and an internal or oblique layer, one layer 

 passing, over into another in many places. At the pylorus the musculature forms 

 a circular sphincter-rmiscle (sphincter of the pylorus) , whose fibers continue into the 

 pyloric valve. At the cardiac orifice also the muscle-fibers are grouped into a 

 sphincter muscle. 



The movements of the stomach are of two kinds : i . The rotatory- 

 rubbing movement, by means of which the walls of the stomach lying 

 in immediate contact with the ingesta move to and fro with a slow 

 displacing action. These movements succeed one another periodically, 

 each cycle occupying several minutes. 



These movements can be imitated by slowly rolling or mdlding a ball between 

 the palms of the hands by means of rotatory movements of the hands in opposite 

 directions. Indeed, hair swallowed by cattle and dogs is formed into a regular 

 ball in the stomach. The object of this rotatory movement is thoroughly to 

 moisten the surface of the stomach-contents with the secretion of the gastric 

 glands, and at the same time to favor its escape by the pressure and the continu- 

 ous passage of ingesta, as well as to detach the already loosened and softened 

 superficial layers of the food. Further, the admixture of the ingesta with the 

 gastric juice is effected in this way. This movement may be either diminished, in 

 the presence of gastric disease, such as gastric ulcer, or increased, as when there 

 is stenosis or dilatation. 



2. The other kind of movement is a peristalsis of periodic recur- 

 rence, in conjunction with rhythmic opening and closure of the pylorus, 

 as a result of which the partly dissolved gastric contents are little by 

 little propelled into the duodenum, commencing after an interval of fif- 

 teen minutes and ending at about the fifth hour. Each wave lasts 

 twenty seconds, with an interval of from fifteen to twenty seconds 

 between waves. This peristalsis is most active from the pyloric antrum 

 toward the pylorus. According to Rudinger, the longitudinal fibers 

 passing toward the pylorus, in contracting, especially when the pyloric 

 antrum is full, cause dilatation of the pylorus. 



