558 THE ARTERIES 



the lieno-renal ligament, and there l^reaks iiji into numerous branches, which 

 enter the hilum and supjily the organ. In this course it crosses in front of the left 

 crus of the diaphragm and the upper end of the left kidney and is placed above the 

 splenic vein.' 



The branches of the splenic artery are: — (1) The smaller pancreatic; (2) the 

 larger pancreatic; (3) the left gastro-epiploica; (4) the vasa Ijrevia; and (5) the 

 terminal. 



(1) The smaller pancreatic branches come off from the sjilenic at varying 

 intervals, as that vessel courses along the upper margin of the pancreas. They 

 enter and supply the organ. 



(2) The larger pancreatic branch usually arises from the splenic about the 

 junction of its middle with its left third. p]ntering the ])ancreas oblitpiely, it runs 

 from left to right, commonly above, and a little l)ehind, the pancreatic duct, winch 

 it supplies together with the substance of the organ. 



(3) The left gastro-epiploic arises from the splenic behind the great cul-de-sac 

 of the stomach, and, ])assing between the anterior layers of the great omentum, 

 descends along the greater curvature of the stomach from left to right, and anasto- 

 moses with the right gastro-epiploic. Like that vessel, it gives off ascending or 

 gastric branches to the anterior and posterior surfaces of the stomach respectively, 

 and long slender descending epiploic or omental branches to the great omen- 

 tum which anastomose with like liranches from the right and left colic arteries. 



(4) The vasa brevia come off from the splenic just before it divides into its 

 terminal branches, oftentimes from some of these terminal liranches themselves. 

 Passing from between the folds of the lieno-renal ligament into those of the gastro- 

 splenic, they thus reach the greater cid-dc-sac of the stomach, where, ramifying 

 over both its anterior and posterior surfaces, they anastomose with the gastric and 

 left gastro-epiploica arteries. 



(5) The terminal branches, five to eight or more in number, are given off 

 from the splenic as it lies in the lieno-renal ligament, and, entering the spleen 

 at the hilum, are distributed in the way mentioned in the description of that 

 organ. 



The variations of the splenic artery are neither numerous nor important. (A) It may divide 

 into two branches which reunite, the splenic vein running through the loop thus formed. (B) It 

 may sometimes give oiF branches nornially derived from other vessels, such as the gastric, the 

 middle colic, and the left hepatic. (C) The variations in its origin are mentioned under A'aria- 

 TIONS OF THE Cgeliac Axis (page 555). 



THE SUPERIOR MESENTERIC ARTERY 



The superior mesenteric artery is given off from the front of the aorta a little 

 below the coeliac axis, which it nearly equals in size; sometimes as a common trunk 

 with the axis. Lying at first behind the pancreas and splenic vein, it soon passes 

 forwards between the lower border of that gland and the upper 1:)order of the third 

 portion of the duodenum, and, crossing in front of the duodenum, enters the 

 mesentery, in which it runs from left to right, in the form of a curve with its con- 

 vexity to the left, to the caecum, Avhere it anastomoses with its ileo-colic branch. 

 Its vein lies to its right side above, having previously crossed obliquely in front of 

 the artery from left to right. It is surrounded liy the mesenteric plexus of nerves. 

 The accessory portion of the head of the pancreas dips in l)ehind the vessel. 



From the concave side of the artery brandies are given oft' to the duodenum and 

 the colon, viz. : — 



(1) The inferior pancreatico-duodcnal; (2) the middle colic; (3) the right colic; 

 and (4) the ileo-colic. 



From the convex side branches are given off to the small intestines, viz. : — 



(5) The vasa intestini tenuis. 



It will thus be seen that the superior mesenteric artery supplies, witli the excej)- 

 tion of the upper third of tlie duodenum, the whole of the small intestine and lialf 

 the large. 



(1 j The inferior pancreatico-duodenal arises either from the superior mesen- 



