ABDOMEN. 



257 



Dissection. Locate the main stems of the artery and vein as they emerge 

 from the under border of the pancreas, gently thrust your forceps never the 

 scalpel through the upper layer of. the mesentery, then use your fingers instead 

 of the forceps and you can easily strip off the remainder of the peritoneum out 

 to the intestinal margin of the mesentery. Trace out with your forceps, by 

 removing the mesenteric connective tissue, always in the direction of the vessel, 

 the following branches: (i) The ileocolic branch to the appendix, caecum, 

 ascending colon, and ileum ; (2) the right colic artery to the ascending colon ; 

 (3) the middle colic artery to the transverse colon ; (4) the main bulk of the 

 artery to the jejunum and ileum under the name of intestinal branches or vasa 



Left colic artery 



Superior mesen- 

 teric artery and 

 vein 



Ileo-colic artery 



VERMIFORM 

 APPENDiX 



Vasa intestini 

 tennis 



SMALL INTESTINES 



FIG. 180. THE SUPERIOR MKSENTERIC ARTERY AND VEIN. 

 (The colon is turned up, and the small intestines are drawn over to the left side.) 



intestini tenuis ; (5) a small branch already found the inferior pancreatico- 

 duodenalis. The veins must be dissected at the same time. If now you will 

 thoroughly wash the mesenteric fat away with ether, and permit the specimen to 

 dry, the sympathetic nerves accompanying the arteries may be seen. 



The Inferior Mesenteric Artery. To dissect this artery and its accompany- 

 ing vein, take the mass of jejunum and ileum far over to the right side. (Fig. 181.) 

 Locate the main stem of the artery at its origin from the abdominal aorta, 

 make a hole through the peritoneum, and, as in the dissection above described, 

 strip off the peritoneum. Now trace out the following branches : (i) The sig- 

 moid artery to the sigmoid flexure of the descending colon ; (2) the superior 



