THE ORGANS OF DIGESTION. 



gland. Considerably augmented in size, it reaches the. neck, and turning obliquely 

 downward, backward, and to the right, it comes into relation with the common bile- 

 duct, lying to its left side ; leaving the head of the gland, it passes very obliquely 

 through the mucous and muscular coats of the duodenum, and terminates by an orifice 

 common to it and the ductus communis choledochus upon the summit of an elevated 

 papilla, situated at the inner side of the descending portion of the duodenum, three 

 or four inches below the pylorus. 



Sometimes the pancreatic duct and ductus communis choledochus open separately 

 into the duodenum. Occasionally there is an accessory duct, which is given off 

 from the canal of Wirsung in the neck of the pancreas and passes horizontally to 

 the right to open into the duodenum about an inch above the orifice of the main 

 duct. This is known as the ductus pancreaticus accessorius or ductus Santorini, 



The pancreatic duct, near the duodenum, is about the size of an ordinary quill : 

 its Avails are thin, consisting of two coats, an external fibrous and an internal mucous ; 

 the latter is smooth, and furnished near its termination with a few scattered follicles. 



In structure, the pancreas resembles the salivary glands. It differs from them, 

 however, in certain particulars, and is looser and softer in its texture. It is not 

 enclosed in a distinct capsule, but is surrounded by areolar tissue, which dips into 

 its interior, and connects together the various lobules of which it is composed. Each 

 lobule, like the lobules of the salivary glands, consists of one of the ultimate rami- 

 fications of the main duct, terminating in a number of csecal pouches or alveoli, 

 which are tubular and somewhat convoluted. The minute ducts connected with the 

 alveoli are narrow and lined with flattened cells. The alveoli are almost completely 

 filled with secreting cells, so that scarcely any lumen is visible. In some animals 

 those cells which occupy the centre of the alveolus are spindle-shaped, and are 

 known as the centro-acinar cells of Langerhans. The true secreting cells which 

 line the wall of the alveolus are very characteristic. They are columnar in shape 

 and present two zones : an outer one clear and finely striated next the basement- 

 membrane, and an inner granular one next the lumen. During activity the granular 

 zone occupies the greater part of the cell : before the cells are called into action, 

 while in a condition of rest, the outer or clear zone is the larger. In some secret- 

 ing cells of the pancreas is a spherical mass, staining more easily than the rest of 

 the cells; this is termed the paranucleus, and is believed to be an extension from 

 the nucleus. The connective tissue between the alveoli presents in certain parts 

 collections of cells, which are termed inter-alveolar cell-islets. 



Vessels and Nerves. The arteries of the pancreas are derived from the splenic 

 and the pancreatico-duodenal branches of the hepatic and the superior mesenteric. 

 Its veins open into the splenic and superior mesenteric veins. Its lymphatics termi- 

 nate in the lumbar glands. Its nerves are filaments from the splenic plexus. 



Surface Form. The pancreas lies in front of the second lumbar vertebra, and can some- 

 times be felt, in emaciated subjects, when the stomach and colon are empty, by making deep 

 pressure m the middle line about three inches above the umbilicus. 



Surgical Anatomy. The pancreas presents but little of surgical importance. It is occa- 

 sionally the seat of cancer, which usually affects the head or duodenal end, and therefore often 

 speedily involves the common bile-duct, leading to persistent jaundice. Cysts are also occasion- 

 ally lound m it, which may present in the epigastric region, above and to the right of the umbil- 

 icus and may require opening and drainage. The fluid in them contains some of the elements 

 ol the pancreatic secretion and is very irritating, so that, if allowed to come in contact with the 

 skin ot the abdominal wall, it is likely to produce intractable eczema. It has been said that the 

 pancreas is the only abdominal viscus which has never been found in a hernial protrusion ; but 

 even this organ has been found, in company with other viscera, in rare cases of diaphragmatic 

 hernia. 1 he pancreas has been known to become invaginated into the intestine, and portions 

 ot the organ have sloughed off. In cases of excision of the pylorus great care must be exer- 

 cised to avoid wounding the pancreas, as the escape of the pancreatic fluid may be attended 

 with serious results. According to Billroth, it is likely, in consequence of its peptonizing quali- 

 ties, to dissolve the cicatrix of the stomach. 



