1184 



THE DIGESTIVE SYSTEM. 



peritoneum pass downwards. The peritoneum is reflected from off the left surface on to the 

 pancreas and abdominal wall, and forms a fold known as the right gastro-pancreatic fold, while 

 the peritoneal covering of the right side is continued onwards along the whole of this part 

 of the duodenum. 



Pars Descendens. The descending part (O.T. second portion) begins at the neck 

 of the gall-bladder, passes down behind the transverse colon, and ends at the right 

 side of the third or fourth lumbar vertebra. In length it measures 3J or 4 inches 

 (8-7 to 10 cm.). 



Its relations are as follows : It lies on the right of the vertebral column and the interior 

 vena cava, from the first to the third or fourth lumbar vertebra, and is anterior to the pelvis 



Top of omental bursa 



Inferior vena cava 

 Lesser omentum (cut) 



Right triangular 

 ligament of liver 



Left triangular ligament of liver 



I CEsophageal opening in diaphragm 



/ Gastro-phrenic ligament 



/ / Corresponds to ' uncovered area of stomacV 

 Gastro-splenic ligament (cut) 



Transverse colon crossing duodenum 



Head of pancreas 

 Gastro-colic ligament (cut) 



Part of omental bursa 



Phrenico-colic ligament 



Left end of transverse mesocolon 

 Left colic flexure 

 Transverse mesocolon (cut) 

 Root of mesentery (cut) 



FIG. 933. THE PERITONEAL RELATIONS OF THE DUODENUM, PANCREAS, SPLEEN, KIDNEYS, ETC. 



From a body hardened by injections of formalin. When the liver, stomach and intestines were removed the 

 lines of the peritoneal reflections were carefully preserved. The peritoneum is coloured blue. 



of the right kidney, the right renal vessels, and ureter, and also, to a varying extent, the front of 

 the right kidney itself; while, below the level of those structures, it rests upon the psoas major 

 muscle. 



The lateral aspect is in contact with the sloping inferior surfaces of the liver in its superior 

 part, and with the right flexure of the colon below. 



Peritoneal Relations. The anterior aspect is covered by peritoneum, except about its middle, 

 where the root of the transverse mesocolon crosses the duodenum. Not infrequently, the 

 transverse colon has no mesentery, but is itself in direct contact with the wall of the duodenum. 

 In other cases, the colon is in contact with the peritoneal surface of the duodenum, below the 

 line of reflection of the transverse mesocolon. 



The head of the pancreas is in contact with its concave left margin, and occasionally overlaps 

 it anteriorly and posteriorly ; and along the margin of the pancreas, both anteriorly and pos- 

 teriorly, are branches of the superior and inferior pancreatico-duodenal vessels, the veins often 

 forming a dense network on the posterior aspect. 



