rs =.” " _ 
~ 
VISCERAL BRANCHES OF THE ABDOMINAL AORTA. 801 
substance of the liver and accompany the branches of the portal vein and the hepatic 
duct. As it crosses just above the junction of the hepatic and cystic ducts, the right 
hepatic artery gives off a cystic branch. The cystic artery (a. cystica) runs downwards 
and forwards along the cystic duct to the gall-bladder, where it divides into upper and 
lower branches; the upper passes downwards between the gall-bladder and the under 
surface of the liver, to both of which it gives offsets ; the lower branch is distributed on 
the under surface of the gall-bladder, between it and the peritoneum. The left hepatic 
artery (ramus sinister) is longer and narrower than the right. It runs to the left end 
of the transverse fissure, gives one or two branches to the Spigelian lobe, crosses the 
i) 
Hh Pancreas 
| Duodeno- 
~ jejunal flexure 
Middle colic artery 
Superior 
mesenteric 
artery 
Inferior pancreatico- 
duodenal artery — 
| Rami intestini 
TY tenuis 
Right colic artery 
Ileo-colic artery 
Termination of 
superior inesen- § 
teric artery f 
Fic. 568.—THE SUPERIOR MESENTERIC ARTERY AND ITS BRANCHES. 
longitudinal fissure, and breaks up into branches which terminate in the substance of the 
left lobe of the liver. 
2. The superior mesenteric artery (a. mesenterica superior, Figs. 566, 568, 
and 591) springs from the front of the aorta, about half-an-inch below the origin 
of the celiac axis and opposite the first lumbar vertebra. 
It passes obliquely downwards and forwards, crossing in front of the left renal 
vein, the lower part of the head of the pancreas, and the third part of the duo- 
denum; opposite the latter it enters the root of the mesentery, in which it 
continues to descend, curving obliquely from above downwards and to the right, to 
51 
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