THE MOVEMENTS OF THE STOMACH. 509 



fibres are supposed to assist, by their contraction, in the process of 

 absorption. 



The innermost, or mucous coat of the stomach, is a soft, pulpy, 

 smooth membrane, of a pale straw color, after death, but of a pink, or 

 bright red, hue during life, being much darker during digestion. It 

 is habitually moistened with mucus. It adheres firmly to the areolar 

 or submucous coat, and follows the folds or rugce seen in the empty 

 stomach, but which are completely obliterated when this organ is dis- 

 tended. The mucous membrane is provided with multitudes of glands, 

 to be hereafter described, which secrete the gastric juice. The blood- 

 vessels and lymphatics are numerous. The nerves of the stomach are 

 derived, partly from the large terminal branches of the pneumogastric 

 or vagi nerves, which are joined by the splanchnic branches of the 

 sympathetic, and partly also by the sympathetic branches, proceeding 

 along the arteries from the coeliac or solar plexus. 



The stomach is a dilated portion, or diverticulum, of the alimentary 

 canal, intended for the reception and retention of successive portions 

 of fluid, and of masticated and insalivated solid food, in order that 

 whilst the watery and dissolved parts are absorbed, the solid substances 

 may be subjected to the action of the gastric juice. Besides these 

 purposes, for which it is fitted by the extensibility of its serous and 

 muscular coats, and by the loose rugae of its less expansible submucous 

 and mucous tunics, the stomach also, by aid of its muscular fibres, im- 

 presses peculiar movements upon the food in its interior, and urges 

 onwards through the pylorus, into the small intestine, those portions 

 which are sufficiently softened and digested by the gastric juice. In 

 these movements, the longitudinal fibres shorten the stomach; the cir- 

 cular fibres lessen its diameter, acting peristaltically from its cardiac 

 onwards to its pyloric end, whilst the oblique fibres draw the sides of 

 the organ over the alimentary mass. When the stomach is empty, the 

 several sets of fibres contract in every direction, some narrowing it, 

 and others shortening it, and so reduce it to its smallest possible 

 dimensions. The pyloric part diminishes relatively less than the car- 

 diac portion.. When, however, the stomach contains food, its internal 

 surface is kept in close contact with this, and the different fasciculi of 

 each layer acting consecutively, give rise to complicated movements 

 in certain directions. The combined result of these, is a remarkable 

 rotatory, or churning motion, which urges the food from the great cul- 

 de-sac along the lower border of the stomach, towards the pylorus, and 

 thence back, along the upper border to the great cul-de-sac again, and 

 so on : such rotation is said to occupy from one to three minutes 

 (Beaumont). In order to prevent regurgitation of the food into the 

 oesophagus, especially during effort with the abdominal muscles, the 

 cardiac orifice is kept closed by the circular fibres of the lower end of 

 the oesophagus, aided by the edges of the opening .in the diaphragm ; 

 the pylorus is closed by its proper muscular ring. As the outer layer 

 of the alimentary mass becomes digested, and converted into a pulp, 

 it is pressed by the peristaltic action of the circular fibres, through 

 the pylorus, and escapes at intervals into the duodenum. As this 

 pulpy portion is expelled, fresh layers of the food mass are brought 



