732 



ORGANS OF DIGESTION. 



mucous glands, and are supposed to secrete the gastric mucus. In other parts 

 of the organ, the deep part of each tube is filled with nuclei, and a mass of 

 granules ; above these is a mass of nucleated cells, the upper fourth of the 

 tube being lined by columnar epithelium. These are called the peptic glands, 

 and are the supposed agents in the secretion of the gastric juice. 



Simple follicles are found in greater or less number over the entire surface of 

 the mucous membrane ; they are most numerous near the pyloric end of the 

 stomach, and are especially distinct in early life. The epithelium lining the 

 mucous membrane of the stomach and its alveoli is of the columnar variety. 



Fij;. 400. Minute Anatomy of Mucous Membrane of Stomach. 



AlveoJt 



Slaut/is of Tutull 



fflitltrltatn 



Qrlfln of Tuif 



Epithelial particles 



BUed Vtml 



Vessels and Nerves. The arteries supplying the stomach are, the coronaria 

 ventriculi, the pyloric and right gastro-epiploic branches of the hepatic, the left 

 gastro-epiploic and vasa brevia from the splenic. They supply the muscular 

 coat, ramify in the subrnucous coat, and are finally distributed to the mucous 

 membrane. The veins accompany the arteries, and terminate in the splenic 

 and portal veins. The lymphatics are numerous ; they consist of a superficial 

 and deep set, which pass through the lymphatic glands found along the two 

 curvatures of the organ. The nerves are the terminal branches of the right and 

 left pneumogastric, the former being distributed upon the back, and the latter 

 upon the front part of the organ. A great number of branches from the sym- 

 pathetic also supply the organ. 



THE SMALL INTESTINES. 



The Small Intestine is that part of the alimentary canal in which the chyme 

 is mixed with the bile, the pancreatic juice, and the secretions of the various 

 glands imbedded in the mucous membrane of the intestines, and where the 

 separation of the nutritive principles of the food, the chyle, is effected ; this 

 constitutes chylification. 



The small intestine is a convoluted tube, about twenty feet in length, which 

 gradually diminishes in size from its commencement to its termination. It is 

 contained in the central and lower parts of the abdominal and pelvic cavities, 

 surrounded above and at the sides by the large intestine; in relation, in front, 

 with the great omenturn and abdominal parietes ; and connected to the spine 

 by a fold of peritoneum, the mesentery. The small intestine is divisible into 

 three portions, the duodenum, jejunum, and ileum. 



The duodenum has received its name from being about equal in length to the 

 breadth of twelve fingers (eight or ten inches). It is the shortest, the widest, 

 and the most fixed part of the small intestine; it has no mesentery, and is only 

 partially covered by the peritoneum. Its course presents a remarkable curve, 

 somewhat like a horseshoe in form ; the convexity being directed towards the 

 right, and the concavity to the left, embracing the head of the pancreas. Com- 

 mencing at the pylorus, it ascends obliquely upwards and backwards to the 

 under surface of the liver ; it then descends in front of the right kidney, and 



