314 



DISSECTION OF THE ABDOMEN. 



lleo-c*cal 

 fold and 

 pouch . 



Ileo-eolic 

 fold and 

 pouch. 



fold (ileo-ccecal), mostly containing fat, passes from the lower border 

 of the last three inches or so of the ileum on to the caecum and 

 appendix, often producing a deep pouch looking downwards and to 

 the left. 



A small ileo-colic fold, produced by a branch of the ileo-colic artery, 

 is sometimes seen immediately above the ileo-colic junction, producing 

 a pouch looking upwards. 



Examine 

 first vessels 

 to intestine. 



Mesenteric 



vessels. 



Dissection 

 of superior 

 mesenteric 



vessels, 



and nerves. 



Superior 



mesenteric 



artery 



courses in 

 the me- 

 sentery ; 



illations, 



and 

 branches 



MESENTERIC VESSELS AND SYMPATHETIC NERVES. 



Directions. The mesenteric vessels and nerves, which supply the 

 greater part of the alimentary tube, may be first dissected. After 

 these have been examined and the relations of the aorta and vena 

 cava have been learnt, most of the intestine will be taken out for 

 examination and to give room for the display of the viscera and 

 vessels in the upper part of the abdomen. 



MESENTERIC VESSELS. The superior and inferior mesenteric 

 arteries are two large branches of the aorta, which supply the 

 intestine, except a part of the duodenum and some of the rectum. 

 Each is accompanied by a vein, and by a plexus of the sympathetic 

 nerve. 



Dissection (fig. 116). For the dissection of the superior 

 niesenteric vessels and nerves, the transverse colon and the great 

 omentum are to be lifted up and placed over the margin of the 

 ribs. The small intestines should be drawn over to the left, and spread 

 out fanwise, so that the anterior or right layer of the mesentery can 

 be removed. While tracing the branches of the artery to the small 

 intestine, corresponding veins and slender offsets of the sympathetic 

 nerve on the arteries will be met with. Mesenteric glands and 

 lacteal vessels also come into view at the same time. 



The branches from the right side of the vessel to the large intes- 

 tine are to be next followed under the peritoneum ; and after all 

 the branches have been cleaned, the trunk of the artery should be 

 traced back beneath the pancreas. The .surrounding plexus of 

 nerves should also be defined. 



The SUPERIOR MESENTERIC ARTERY (fig. 116, ) supplies all the 

 small intestine beyond the duodenum and half the large intestine, 

 viz., as far as the end of the transverse colon. 



Arising from the aorta near the diaphragm, it is directed down- 

 wards between the layers of the mesentery, forming an arch with 

 the convexity to the left side, and terminates in offsets to the 

 end of the small intestine. At first the artery lies beneath the 

 pancreas and the splenic vein ; and as it descends to the mesentery 

 it is placed in front of the left renal vein and the duodenum. It is 

 surrounded by a plexus of nerves, and accompanied by the vein of 

 the same name. 



BRANCHES. The artery furnishes a small offset to the pancreas 

 and duodenum, intestinal branches to the jejunum and ileum, and 

 colic branches to the large intestine. 



