PHYSIOLOGICAL ANATOMY OF THE STOMACH. 211 



CHAPTER VIII. 



GASTRIC DIGESTION. 



Physiological anatomy of the stomach Glands of the stomach Closed follicles Gastric jnice Gastric 

 fistula in the human subject in the case of St. Martin Secretion of the gastric juice Properties and 

 composition of gastric juice Action of the gastric juice in digestion Peptones Action of the gastric 

 juice upon fats, sugars and amylaceous substances Duration of gastric digestion Conditions which in- 

 fluence gastric digestion Movements of the stomach. 



PHYSIOLOGICAL ANATOMY OF THE STOMACH. 



THE stomach serves the double purpose of a receptacle for the food and 

 an organ in which certain important digestive processes take place. It is 

 situated in the upper part of the abdominal cavity and is held in place by 

 folds of the peritoneum and by the ossophagus. Its form is not easily de- 

 scribed. It has been compared to a bagpipe, which it resembles somewhat, 

 when moderately distended. When empty, it is flattened, and in many parts 

 its opposite walls are in contact. When moderately distended, its length is 

 thirteen to fifteen inches (33 to 38 centimetres), its greatest diameter, about 

 five inches (12'7 centimetres), and its capacity, one hundred and seventy-five 

 cubic inches (2,868 c. c.), or about five pints. The parts usually noted in 

 anatomical descriptions are the following : a greater and a lesser curvature ; 

 a greater and a lesser pouch; a cardiac, or oesophageal opening; a pyloric 

 opening, which leads to the intestinal canal. The great pouch is sometimes 

 called the fundus. 



The coats of the stomach are three in number ; the peritoneal, muscular 

 and mucous. By some anatomists the fibrous tissue which unites the mucous 

 to the muscular coat is regarded as a distinct covering and is called the 

 fibrous coat. 



Peritoneal Coat. This is simply a layer of peritoneum, similar in struct- 

 ure to the membrane which covers the other abdominal viscera. It is a re- 

 flection of the membrane which lines the general abdominal cavity, which, 

 on the viscera, is somewhat thinner than it is on the walls of the cavity. 

 Over the stomach the peritoneum is -3^-5- to ^J-g- of an inch (83 to 125 ft) 

 in thickness. It is a serous membrane and consists of ordinary fibrous 

 tissue with a considerable number of elastic fibres. It is closely adherent 

 to the subjacent muscular coat and is not very abundantly supplied with 

 blood-vessels and nerves. Lymphatics have been demonstrated only in the 

 subserous structure. The surface of the peritoneum is everywhere covered 

 with regularly polygonal cells of pavement endothelium, closely adherent to 

 each other and presenting a perfectly smooth surface which is moistened 

 with a small quantity of liquid. An important office of this membrane is to 

 present a smooth surface covering the abdominal parietes and viscera, so as 

 to allow free movements of the organs over each other and against the walls 

 of the abdomen. 



Muscular Coat. Throughout the alimentary canal, from the cardiac 

 opening of the stomach to the anus, the muscular fibres forming the middle 

 coat are of the non-striated variety. These fibres, called sometimes muscu- 



