DIGESTION. 251 



the viscus, highly conducive to their free mixture with the gastric fluid 

 and to their ready digestion. 



Vomiting. The expulsion of the contents of the stomach in vomit- 

 ing, like that of mucous or other matter from the lungs in coughing, is 

 preceded by an inspiration; the glottis is then closed, and immediately 

 afterward the abdominal muscles strongly act; but here occurs the dif- 

 ference in the two actions. Instead of the vocal cords yielding to the 

 action of the abdominal muscles, they remain tightly closed. Thus the 

 diaphragm being unable to go up, forms an unyielding surface against 

 which the stomach can be pressed. In this way, as well as by its own 

 contraction, it is fixed, to use a technical phrase. At the same time the 

 cardiac sphincter-muscle being relaxed, and the orifice which it naturally 

 guards being actively dilated, while the pylorus is closed, and the stomach 

 itself also contracting, the action of the abdominal muscles, by these 

 means assisted, expels the contents of the organ through the oesophagus, 

 pharynx, and mouth. The reversed peristaltic action of the oesophagus 

 probably increases the effect. 



It has been frequently stated that the stomach itself is quite passive 

 during vomiting, and that the expulsion of its contents is effected solely 

 by the pressure exerted upon it when the capacity of the abdomen is 

 diminished by the contraction of the diaphragm, and subsequently of the 

 abdominal muscles. The experiments and observations, however, which 

 are supposed to confirm this statement, only show that the contraction of 

 the abdominal muscles alone is sufficient to expel matters from an unre- 

 sisting bag through the ossophagus; and that, under very abnormal 

 circumstances, the stomach, by itself, cannot expel its contents. They by 

 no means show that in ordinary vomiting the stomach is passive; and, 

 on the other hand, there are good reasons for believing the contrary. 



It is true that facts are wanting to demonstrate with certainty this 

 action of the stomach in vomiting; but some of the cases of fistulous open- 

 ing into the organ appear to support the belief that it does take place; 

 and the analogy of the case of the stomach with that of the other hollow 

 viscera, as the rectum and bladder, may be also cited in confirmation. 



The muscles concerned in the act of vomiting, are chiefly and pri- 

 marily those of the abdomen; the diaphragm also acts, but usually not as 

 the muscles of the abdominal walls do. They contract and compress the 

 stomach more and more toward the diaphragm; and the diaphragm 

 (which is usually drawn down in the deep inspiration that precedes each 

 act of vomiting) is fixed, and presents an unyielding surface against 

 which the stomach may be pressed. The diaphragm is, therefore, as a 

 rule, passive during the actual expulsion of the contents of the stomach. 

 But there are grounds for believing that sometimes this muscle 

 actively contracts, so that the stomach is, so to speak, squeezed between 

 the descending diaphragm and the retracting abdominal walls. 



