BRANCHES OF THE ABDOMINAL AORTA. 225 



tributed to all the small intestines and to the right side of the 

 large one after the following manner: it first passes behind the 

 pancreas, and then in front of the duodenum, to reach the rjaot 

 of the mesentery, between the two laminae of which it divides 

 and subdivides into several series of arches, one after another: 

 they become successively smaller and more numerous till they 

 reach the margin of the intestine, where they cease by sending 

 a great many small parallel branches. 



The trunk of the superior mesenteric artery, in descending 

 between the laminae of the mesentery, describes a considera- 

 ble curvature, the convexity of which is to the left side and 

 downwards, while its concavity is in a contrary direction. It 

 is from the convexity of this trunk, that from fifteen to twenty 

 large branches are sent off successively to form the roots of the 

 first row of arterial arches. These branches are shorter, and 

 generally somewhat smaller, the lower down they arise; and 

 their origins very closely succeed each other. Upon the first 

 row of arches or anastomoses is formed a second more nume- 

 rous and small, and upon the second row is formed a third 

 still more numerous and small, from which proceed the intes- 

 tinal branches. 



Besides the preceding branches, the superior mesenteric ar- 

 tery sends off the following: 



Near its root several small ramifications arise, which go to 

 the duodenum and to the pancreas, and anastomose there with 

 the other arteries supplying the same organs. 



From about the middle of the concavity of the superior me- 

 senteric artery, arise the three Colic arteries called lleo-colica, 

 Colica Dextra, and Colica Media: the first supplies a cluster of 

 branches to the lower part of the ileum and to the head of the 

 colon, anastomosing on the left with the last of the small intes- 

 tinal arteries and on the right with the colica dextra : the Co- 

 lica Dextra is smaller than either of the other two branches, 

 and goiwg between the laminae of the mesocolon, supplies the 

 ascending portion of the colon by dividing into two principal 

 branches, one of which anastomoses with the ileo-colic ar- 

 tery, and the other with the colica media: the Colica Media, 

 situated between the laminae of the transverse mesocolon, and 

 arising higher up than the colica dextra, advances forwards and 



