MOVEMENTS OF THE STOMACH 203 



Movements of the Stomach. As food is passed into the stomach, 

 the organ gradually changes its form, size and position. When the 

 stomach is empty, the opposite surfaces of its lining membrane are in 

 contact in many parts and are thrown into longitudinal folds. As the 

 organ is distended, these folds are effaced, the stomach itself becoming 

 more rounded, and as the two ends, with the lesser curvature, are com- 

 paratively immovable, the stomach undergoes a movement of rotation, 

 by which the anterior face becomes superior and is applied to the dia- 

 phragm. At this time the great pouch has nearly filled the left hypo- 

 chondriac region ; and the great curvature presents anteriorly and comes 

 in contact with the abdominal walls. Aside from these changes, which 

 are due merely to distention, the stomach undergoes important move- 

 ments, which continue until its contents have been dissolved and 

 absorbed or have passed out at the pylorus ; but while these move- 

 ments are taking place, the two orifices are guarded, so that the food 

 shall remain for the proper time exposed to the action of the gastric 

 juice. By the rhythmical contractions of the lower extremity of the 

 oesophagus, regurgitation of food is prevented ; and the circular fibres, 

 which form a thick ring at the pylorus, are constantly contracted, so 

 that at least during the first periods of digestion only liquids and 

 that portion of food which has been reduced to a pultaceous consistence 

 can pass into the small intestine. It is well known that this resistance 

 at the pylorus does not endure indefinitely, for indigestible articles of 

 considerable size, such as stones, have been passed by the anus after 

 having been introduced into the stomach; but observations have shown 

 that masses of digestible matter are passed by the movements of the 

 stomach to the pylorus, over and over again, and that they do not find 

 their way into the intestine until they have become softened and more 

 or less disintegrated. 



The contractions of the walls of the stomach are of the kind charac- 

 teristic of non-striated muscular fibres. If the finger is introduced into 

 the stomach of a living animal during digestion, it is gently but rather 

 firmly grasped by a contraction, which is slow and gradual, enduring 

 for a few seconds and as slowly and gradually relaxing and extending 

 to another part of the organ. The movements during digestion present 

 certain differences in different animals ; but there can be no doubt that 

 the phenomenon is universal. In dogs, when the abdomen is opened 

 soon after the ingestion of food, the stomach appears pretty firmly con- 

 tracted on its contents. In a case reported by Todd and Bowman, in 

 the human subject, in which the stomach was much hypertrophied and 

 the walls of the abdomen were very thin, the vermicular movements 

 could be distinctly seen. These movements were active, resembling the 



