882 THE PANCREAS. 



inch to an inch in thickness, being thicker at its head and along its upper border than 

 elsewhere. The weight of the gland, according to Krause and Clendenning, is 

 usually from 1\ oz. to 3| oz. ; but Meckel has noted it as high as 6 oz., and Soemmer- 

 ring as low as 1| oz. 



The anterior surface of the pancreas is covered with the posterior wall of 

 the sac of the omentum, and is concealed by the stomach, which glides upon 

 it. The posterior surface is attached by areolar tissue to the vena cava, the 

 aorta, the superior inesenteric artery and vein, the commencement of the 

 vena portse, and the pillars of the diaphragm, all of which parts, besides 

 many lymphatic vessels and glands, are interposed between it and the upper 

 lumbar vertebrae : to the left of the vertebral column it is attached simi- 

 larly to the left suprarenal capsule and kidney and to the renal vessels. Of 

 the large vessels situated behind the pancreas, the superior inesenteric artery 

 and vein are embraced by the substance of the gland, so as sometimes to be 

 enclosed in a complete canal, through which they pass downwards and for- 

 wards, and then emerge from beneath the lower border of the pancreas, 

 between it and the termination of the duodenum. The coeliac axis is above 

 the pancreas ; and in a groove along the upper border of the gland are placed 

 the splenic artery and vein, the vein pursuing a straight, and the artery a 

 tortuous course, and both supplying numerous branches to the pancreas, the 

 narrow extremity of which is thus attached to the inner surface of the spleen. 

 The head of the pancreas, embraced by the inner curved border of the duo- 

 denum, is attached more particularly to the descending and transverse por- 

 tions of that intestine, beyond which it projects somewhat both in front and 

 behind. The ductus communis choledochus passes down behind the head 

 of the pancreas, and is generally received into a groove or canal in its 

 substance. 



Structure. The pancreas belongs to the class of conglomerate glands. lu 

 its general characters, and also in its intimate structure, which is racemose, it 

 closely resembles the salivary glands, but it is somewhat looser and softer in 

 its texture. It consists of numerous lobes and lobules, of various sizes, 

 held together by areolar tissue, blood-vessels, and ducts. The lobules, 

 aggregated into masses, are rounded or slightly flattened at the sides, so as 

 to be moulded or adjusted compactly to each other ; their substance is of a 

 reddish cream-colour, and the arrangement of the commencing ducts and 

 vessels is similar to that in the lobules of the parotid gland, which has been 

 already described (p. 816). 



The principal excretory duct, called the pancreatic duct or canal of 

 Wirsung (by whom it was discovered in the human subject in 1642), runs 

 through the entire length of the gland, from left to right, buried completely 

 in its substance, and placed rather nearer its lower than its upper border. 

 Commencing by the union of the small ducts derived from the groups of 

 lobules composing the tail of the pancreas, and receiving in succession at 

 various angles, and from all sides, the ducts from the body of the gland, 

 the canal of Wirsung increases in size as it advances towards the head of 

 the pancreas, where, amongst other large branches, it is usually joined by 

 one derived from that portion of the gland called the lesser pancreas. 

 Curving slightly downwards, the pancreatic duct Hhen comes into contact 

 with the left side of the ductus communis choledochus, which it accom- 

 panies to the back part of the descending portion of the duodenum. Here 

 the two ducts, placed side by side, pass very obliquely through the muscular 

 and areolar coats of the intestine, and terminate, as already described 

 (p. 868), on its internal mucous surface, by a common orifice, situated at 



