86 



PANCREAS. 



duodenum.* Towards its orifice the duct 

 more or less enlarges itself ; but at its very 

 aperture, on the contrary, it undergoes a 

 contraction. The appearance of a valve 

 guarding the orifice depends merely on the 

 partition which separates its mouth from that 

 of the choledoch duct. Occasionally near the 

 orifice, occasionally higher up, there is a 

 valve-like process "projecting from its inner 

 surface ; but this is not constant either in its 

 situation or its existence. 



From the narrowness of the duodenal ori- 

 fice of the pancreatic duct, from the movable 

 and yielding nature of the eminence upon 

 which it opens, and from the oblique course 

 of the duct through the walls of the duo- 

 denum, it follows that the pancreatic fluid 

 and the bile may pass freely into the duode- 

 num, but cannot regurgitate from it into the 

 ducts. " On this subject," says Cruveilhierf , 

 " I have made several experiments. I have 

 forcibly injected both water and air into the 

 duodenum, included between two ligatures, 

 but nothing escaped; on the other hand, I 

 have injected the same fluids from the duct 

 into the duodenum, which I was thus able 

 to distend at pleasure. But then, on com- 

 pressing the bowel with great force, I have 

 never been able to cause the slightest re- 

 flux into the ducts." The spur-like process 

 formed by the lining membrane reflected 

 upon itself at the junction of the ductus 

 choledochus and the pancreatic duct, ex- 

 tending down to the duodenal orifice, does 

 not prevent the fluid of one canal from passing 

 into the other. Thus the pancreatic fluid might 

 regurgitate into the ductus choledochus, and, 

 on the other hand, the bile might enter the 

 pancreatic duct, if these canals were not 

 habitually full. Moreover, this spur-shaped 

 process between the two canals cannot arrest 

 the flow either of the bile or pancreatic fluid, 

 by being applied to the orifice of the one or 

 the other duct. 



Fig. 56. is a diagrammatic representation of 

 the manner in which the ducts traverse the 

 walls of the duodenum and terminate in the 

 papilla, and of their relation to one another, 

 and to the coats of the intestine. 



Vessels. The arteries of the pancreas, 

 which, for the size of the gland, are large and 

 numerous, are, like those of other conglomerate 

 glands, contributed from many sources, and 

 are derived from the branches of the coeliac 

 axis, and from the superior mesenteric. The 

 principal are thepancreatico-duodenalis of the 

 hepatic and the pancreatic branches of the 

 splenic artery, one of which, the pancrea- 

 tica magna, sometimes runs nearly the whole 



* Scemmerring considers the apposition of the 

 two ducts in the wall of the intestine a junction, 

 and the partition between them merely a valve : 

 indeed, it is to that portion of the bile duct, so 

 joined by the pancreatic, that he restricts the ap- 

 pellation ductus choledochus. " Ductus choledoch us, 

 id est ductus hepaticits, cysticus, et pancreaticus in 

 unum confuti." (Corp. Hum. Fab.) A definition 

 as unphysiologieal as it is inconsistent with critical 

 anatomy. 



f Descriptive Anatomy. 



length of the gland, accompanying the duct 

 The branches from the 



Fig. 56. 



from left to right. 



Diagram of the normal method of termination of the 

 pancreatic and bile-ducts in the human subject, 

 showing their oblique transit through the successive 

 elements of the wall of the intestine, their gradual 

 approximation to one another, their final union at 

 the base of the ampulla or cavity of the papilla, and 

 the spur-like process separating them, 

 a is the bile-duct ; b, the pancreatic ; c, d, and e, 



the muscular and mucous coats of the intestine. 



superior mesenteric are mostly derived from 

 that small twig which, given off just at the 

 lower border of the pancreas, anastomoses 

 with the pancreatico-duodenalis. The veins 

 empty themselves into the superior mesenteric 

 and splenic. 



The lymphatic vessels have not, that I know 

 of, been demonstrated, nor have I been able 

 to detect them myself: they are supposed to 

 enter the lumbar glands in the neighbourhood. 



The nerves are derived from the solar plexus, 

 and enter the gland at different parts, accom- 

 panying the branches from the arteries of the 

 coeliac axis. 



II. MICROSCOPICAL ANATOMY. 



Gland substance. The subject of the micro- 

 scopical anatomy of the pancreas is one of great 

 difficulty, and, until I came to examine it for 

 myself, I had no idea how great. The deli- 

 cacy and tenuity of the structures, even when 

 seen most advantageously ; the destruction of 

 all their natural relations, and consequent im- 

 pairment of the value of observations by cut- 

 ting, tearing, or compression ; the rapid change 

 that takes place in the microscopical elements 

 themselves, in whatever medium they are 

 placed for examination, by deliquescence, so- 

 lution, or endosmosis; the conflicting character 

 of different appearances ; and the discrepancy 

 of many of them with the interpretations 



