chap, xvii.] ABDOMINAL VISCERA. 339 



In connection with the spread of disease by con- 

 tinuity of tissue, it is well to note that the duodenum 

 is in relation with the liver, gall bladder, pancreas, 

 transverse colon, spine, right kidney, bile duct, portal 

 vein, gastro-duodenal and superior mesenteric vessels, 

 aorta and vena cava. 



In the duodenum are Brunner's glands, which are 

 sometimes the seat of a perforating ulcer in cases of 

 burns. They are mostly seated in the first segment 

 of this bowel, and the perforation, therefore, usually 

 opens into the peritoneal cavity. 



The peculiar vertical curve of the duodenum 

 closely resembles that of the syphon trap used in 

 drains. Mr. Mayo Collier has pointed out that this 

 part of the bowel probably acts as a real syphon trap, 

 and so prevents the regurgitation of intestinal gas 

 into the stomach. The duodenum of the horse appeal's 

 to act also in this manner. 



Passing from the front of the terminal (ascending) 

 part of the duodenum, a fold of peritoneum is often 

 seen, that joins the parietal peritoneum to the left of 

 the piece of gut in question. This fold marks off a 

 fossa of triangular outline, the orifice of which is 

 directed upwards. I have found the fossa in about 

 50 per cent, of the bodies examined. It is called the 

 fossa duodeno -jejuualis ; it is usually large 

 enough to lodge the tip of the finger, and its opening 

 lies just below the duodeno-jejunal bend. This fossa 

 is the anatomical cause of mesenteric or retro-peritoneal 

 hernia. The commencement of the jejunum pi-esses 

 into the fossa, enlarges its cavity, and ultimately 

 separates the peritoneum from its posterior attach- 

 ments. More and more of the small intestine passes 

 into the increasing pouch, until at last, as in the 

 case reported by Sir Astley Cooper, nearly the 

 whole of the small intestine may be found lodgfil 

 in an enormous median retro-peritoneal sac, the 



