424 Arteries of the Trunk. 



ca) Rami panci-catici, numerous, to the corpus and to the cauda pancreatis. 



cb) A. gastroepiploica sinistra (left g-astroepiploic artery) (see also fig. 465) runs forward 



in the lig. gastrolienale, goes to the right, between the two anterior layers of the 

 omentum majus, along the curvatura major of the stomach, and unites with the 

 a. gastroepiploica dextra ; its branches are like those of the latter artery. 



cc) Aa. (jastricae breoes (vasa brevia) (see Fig. 464). in the lig. gastrolienale to the 



fundus ventriculi. 

 cd) Rami lienaUs fmni the hilus to the substance of the spleen (see Fig. 586). 



5. A. meseuterica superior (superior mesenteric artery) (see also Figs. 463 465, 498 

 and 584), unpaired, arises just below the a. coeliaca, separated from it by the v. lienalis, in front 

 of the 1st lumbar vertebra; it goes downward at first behind the caput pancreatis, then passes 

 through the incisura pancreatis in the groove on the anterior surface of the processus uncinatus 

 and in fi-ont of the pars inferior duodeni between the layers of the mesenterium and runs in 

 a curve, slightly convex to the left and forward, as far as the first portion of the large intestine. 



a) A. pancreaticoduodcnalis inferior (see Fig. 464) goes off from the right side, runs to 



the right on the concave surface of the pars inferior duodeni between it and the 

 pancreas, supplies both organs and unites with the a. pancreaticoduodenalis superior. 



b) Aa. intesiinates (0. T. vasa intestini tenuis), about sixteen, fi'om the convexity of the 



arch, pass between the layers of the mesenterium to the loops of the jejunum (aa. 

 jcjunaks) and ileum (aa. ileae). Each artery bifurcates and forms arch-like anasto- 

 moses with the branches of neighboring vessels ; the branches arising from these form 

 further anastomoses and so on until two to five series of anastomoses follow upon 

 one another (see Fig. 496). From the last -iiumerous branches of nearly equal sife and 

 almost equidistant from one another go to the small intestine. Small branches go 

 also to the contents of the mesentery. The last a. ilea unites with the a. ileocolica. 



c) A. ileocolica, from the right side, runs behind the peritonaeum to the right and 



downward to the end of the small and beginning of the large intestine, anastomoses 

 with the last a. ilea and with the a. colica dextra. A small branch, the a. ajrpen- 

 dicularis (not indicated), goes behind the ileum "to the vermiform process. 



d) A. colica dextra (right colic artery), fi-ora the right side, very often a branch of the 



preceding arteiy, goes to the right behind the peritonaeum to the colon ascendens; 

 it anastomoses with the a. ileocolica and with the a. colica media. 



e) A. colica media (middle colic artery), from the right side, in frunt Lif the pancreas; 



it extends to the right and forward in the mesocolon transversum to the colon trans- 

 versum; it anastomoses with the a. colica dextra and with the a. colica sinistra. 



6. A.mesenterica iuferior (see Figs. 462465), unpaired, arises between the 3rd and 

 4th lumbar vertebra and runs downward and to the left, beneath the peritonaeum. Branches: 



a) A. colica sinistra (left colic artery), beneath the peritonaeum to the left to the colon 



descendens; it anastomoses with the a. colica media and with the aa. sigmoideae. 



b) Aa. sigmoideae, often single, run downward and to the left to the colon sigmoideum: 



they anastomose with the a. colica sinistra and with the a. haemorrhoidalis superior. 



c) A. haemorrhoidalis superior (see also Figs. 470 and 471) bends downward in fi-ont 



of the a. and v. iliaca communis sinistra and in front of the promontorium and goes 



downward between the two layers of the mesorectum, in front of the sacrum and 



behind the rectum, and then divides into two branches, which run right and left to 



the intestinum rectum; it anastomoses above with the aa. sigmoideae, below witli 



the aa. haemorrhoidales mediae (from the a. hyppgastrica). 



A. iliaca communis (iliac artery) (see also Figs. 463, 467, 468, 470, 471 and 499) 



paired, goes downward, lateralward and forward, slightly curved, in front of the bodies of 



the 4th and 5th Uimbar vertebra at the medial margin of the m. psoas major; it is covered by 



jieritonaeum and runs, on the left side, behind the ureter and the a. haemorrhoidalis superior. 



It lies in front of and somewhat to the left of the v. iliaca communis. It divides in front of 



the articulatio sacroiliaca into the a. liypogastrica and the a. iliaca externa. 



A. liypogastrica (see Figs. 463, 467, 468, 470 and 471) turns downward and 

 somewhat backward into the small pelvis and divides, after a short course, usually into a 

 posterior and an anterior branch. The posterior branch bends markedly backward to the upper 

 part of the foramen ischiadicum majus (above the m. piriformis), gives off the aa. iliolumbahs. 

 obturatoria and sacralis lateralis and ends as the a. glutaea superior. The anterior branch 

 runs in ft'ont of the m. piriformis to the inferior portion of the foramen ischiadicum majus, 

 gives off the aa. umbilicalis (or aa. vesicales superiores), vesicalis inferiur. deferentialis (in the 

 male), uterina (in the female) and haemorrhoidalis media and bifurcates into the aa. glutaea 

 inferior and ]Hulenda interna. The subdivisions of the posterior branch (and the a. glutaea in- 

 ferior) go chiefly to the walls of the pelvis as rami parietales, those of the anterior branch 

 (with the exception of the a. glutaea inferior) chietly to the viscera as rami yiscerales. 



