FORM AND RELATIONS OF THE SPLEEN. 883 



the junction of the descending and horizontal portions of the duodenum, 

 between three and four inches below the pylorus. The pancreatic duct, 

 with its branches, is readily distinguished from the glandular substance, 

 by the very white appearance of its thin fibrous walls. Its widest part, 

 near the duodenum, is from 1 line to 1 J line in diameter, or nearly the size 

 of an ordinary quill ; but it may be easily distended beyond that size. It 

 is lined by a remarkably thin and smooth mucous membrane, which near 

 the termination of the duct occasionally presents a few scattered follicles. 



Varieties. Sometimes the pancreatic duct is double up to its point of entrance 

 into the duodenum ; and a still farther deviation from the ordinary condition is not 

 unfrequently observed, in which there is a supplementary duct, derived from the 

 lesser pancreas or some part of the head of the gland, opening into the duodenum by 

 a distinct orifice, at a distance of even one inch or more from the termination of the 

 principal duct. It sometimes occurs that the pancreatic duct and the common bile 

 duct open separately into the duodenum. 



Vessels and Nerves. Like the salivary glands, the pancreas receives its blood- 

 vessels at numerous points. Its arteries are derived from the splenic and from the 

 superior and inferior pancreatico-duodenal branches of the hepatic and superior 

 mesenteric. Its blood is returned by the splenic and superior mesenteric veins. 

 Its lymphatics terminate in the lumbar vessels and glands. The nerves of the 

 pancreas are derived from the solar plexus. 



Development. In its origin and development, the pancreas altogether resembles 

 the salivary glands. It appears a little earlier than these glands, in the form of a 

 small bud from the left side of the intestinal tube, close to the commencing spleen. 



Secretion. Like the saliva, the pancreatic juice is a clear colourless fluid, which 

 has diffused in it a few microscopic corpuscles ; it has an alkaline reaction, and 

 coagulates in white flakes when heated. The coagulum is caused by the presence of 

 an albuminoid substance pancreatin which, like salivin, has the property of con- 

 verting starch into sugar. The pancreatic juice contains likewise chlorides of sodium 

 and potassium, and phosphates of lime, soda, and magnesia. It readily undergoes 

 decomposition on exposure. 



THE SPLEEN. 



The spleen is a soft, highly vascular, and easily distensible organ, of a 

 dark bluish or purplish grey colour. It is situated in the left hypochon- 

 drium, at the cardiac end of the stomach, between that viscus and the dia- 

 phragm, and is protected by the cartilages of the ribs. It is the largest of 

 the structures termed ductless glands, and it is now generally admitted to 

 be intimately connected with the process of sanguification, and is most pro- 

 bably the seat of the formation of blood-corpuscles. 



The shape of the spleen is irregular and somewhat variable : it forms a 

 compressed oval mass, placed nearly vertically in the body, and having two 

 faces, one external, convex, and free, which is turned to the left, the other 

 internal and concave, which is directed to the right, and is applied to the 

 cardiac end or great cul-de-sac of the stomach : it also presents an anterior 

 sharper and a posterior blunter margin. 



The convex face of the spleen, smooth and covered by the peritoneum, is 

 in contact with the under surface of the left side of the diaphragm, and 

 corresponds with the ninth, tenth, and eleventh ribs. The internal concave 

 face is divided by a vertical fissure, named the hilus, into an anterior and 

 posterior portion, both covered with peritoneum, continued round the bor- 

 ders from the convex surface. The anterior of these two portions is the 

 larger, and is closely applied to the stomach ; the posterior is in apposition 

 with the left pillar of the diaphragm and left suprarenal capsule. The 

 anterior border of the spleen is thinner than the posterior, and is often 



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