THE ABDOMEN. 287 



course it gives off important vessels. Coeliac axis, a single 

 trunk, is but a short vessel, for it soon breaks up into 

 three branches, gastric, splenic, and hepatic. The gastric 

 runs direct from its commencement to the central part of 

 the lesser cui-vature of the stomach, where it breaks up in 

 forming the superior and inferior gastric arteries. The 

 splenic inclining to the left side and gaining the base of 

 the' spleen runs along its lesser curvature between the two 

 folds of peritoneum which constitute gastro-splenic omen- 

 tum. During its course it gives off large branches to the 

 spleen, smaller branches to the stomach, and at the apex 

 of the spleen is continued along the greater curvature of 

 the stomach as the left gastric artery. The hepatic artery, 

 which inclines to the right side, has already been de- 

 scribed. 



Anterior mesenteric artery (in the ass extremely liable to 

 aneurism from the presence of parasites of the nematode 

 class — strongylus armatus) arises from the under part of 

 the posterior aorta. It gives off a few branches to the 

 pancreas which completely surrounds it. And then the 

 branches : mesenteric, thirteen to eighteen in number, 

 which radiate through the mesentery to the small intestine ; 

 the first anatomoses with the duodenal branch of the 

 hepatic, the last with the ccecal branch, which in its turn 

 communicates with the tranches to the double colon, and 

 they with that to the single colon, which joins the first 

 branch of the posterior mesenteric artery, a vessel 

 supplying the single colon and rectum in a manner already 

 described ; it arises from the under surface of the posterior 

 aorta just prior to its termination. 



Renal arteries arise from the lateral part of the posterior 

 aorta just behind the anterior mesenteric trunk. They are 

 large vessels, given off at right angles. They are also 

 termed the emulgent arteries, and before arriving at 

 the kidneys break up, sometimes sending a branch to the 

 prerenal capsule (which sometimes arises from the posterior 

 aorta). Most of their branches enter the kidney at a 

 particular notch, in its substance termed the hilum, some 

 run to other parts of the organ. The inclination of the 

 posterior aorta to the left side of the spine renders the 

 right renal artery the longest, for it has to pass under the 

 posterior vena cava. It is also given off more anteriorly than 

 the left. 



