586 THE SPLEEN. 



towards the right, and is surrounded by the curve of the duodenum; 

 the lesser end extends to the left as far as the spleen. The anterior 

 surface of the body of the pancreas is covered by the ascending pos- 

 terior layer of peritoneum, and is in relation with the stomach, the first 

 portion of the duodenum and the commencement of the transverse 

 arch of the colon. The posterior surface is grooved for the splenic vein, 

 and tunneled by a complete canal for the superior mesenteric and portal 

 vein, and for the superior mesenteric artery. The upper border pre- 

 sents a deep groove, sometimes a canal for the splenic artery and vein, 

 and is in relation with the oblique portion of the duodenum, the lobus 

 Spigelii, and coeliac axis. And the lower border is separated from the 

 transverse portion of the duodenum by the superior mesenteric artery 

 and vein. Upon the posterior part of the head of the pancreas is a 

 lobular fold of the gland which completes the canal of the superior 

 mesenteric vessels, and is called the lesser pancreas. 



In structure the pancreas is composed of reddish- yellow polygonal 

 lobules ; these consist of smaller lobules, and the latter are made up of 

 the arborescent ramifications of minute ducts, terminating in caecal 

 pouches. 



The pancreatic duct commences at the papilla upon the inner and 

 posterior surface of the perpendicular portion of the duodenum by a 

 small dilatation which is common to it and the ductus communis cho- 

 ledochus, and passing obliquely between the mucous and muscular coats, 

 runs from right to left through the middle of the gland, lying nearer 

 to its anterior than its posterior surface. At about the commencement 

 of the apicial third .of its course it divides into two parallel terminal 

 branches. It gives off numerous small branches, which are distributed 

 through the lobules, and constitute with the latter the substance of the 

 gland. The duct which receives the secretion from the lesser pan- 

 creas is called the ductus pancreaticus minor; it opens into the prin- 

 cipal duct near the duodenum, and sometimes passes separately into 

 that intestine. As a variety, two pancreatic ducts are occasionally 

 met with. 



Vessels and Nerves. The arteries of the pancreas are branches of 

 the splenic, hepatic, and superior raesenteric ; the veins open into the 

 splenic vein ; the lympliatics terminate in the lumbar glands. The 

 nerves are filaments of the splenic plexus. 



THE SPLEEN. 



The spleen is an oblong flattened organ of a dark-bluish red colour, 

 situated in the left hypochondriac region. It is very variable in size 

 and weight, spongy and vascular in texture and exceedingly friable. 

 The external surface is convex, the internal slightly concave, indent- 

 ed along the middle line, and pierced by several large and irregular 

 openings for the entrance and exit of vessels ; this is the hilus lienis. 

 The upper extremity is somewhat larger than the lower, and rounded; 

 the inferior is flattened ; the posterior border is obtuse, the anterior is 



