458 THE ARTERIES OF THE ABDOMEN. 



The anterior surface of the abdominal aorta is successively in apposition with 

 the pancreas and the splenic vein, the left renal vein, the third portion of the 

 duodenum, and the peritoneum. The vena cava lies along its right side, the right 

 cms of the diaphragm being interposed at the upper part ; close to the same side 

 are the thoracic duct and the large azygos vein, which are placed between the aorta 

 and the crus of the diaphragm. The aorta is also covered in front by the solar and 

 aortic plexuses of the sympathetic nerve, by numerous lymphatic vessels and glands, 

 and by a layer of dense areolar tissue. Behind it are the bodies of the vertebrae and 

 the left lumbar veins. 



BRANCHES. The abdominal aorta gives numerous branches, which may be 

 divided into two sets, viz., those which supply the viscera, and those which are 

 distributed to the walls of the abdomen. The former consists of the coeliac artery, 

 the superior mesenteric, the inferior mesenteric, the suprarenal, the renal, and the 

 spermatic arteries ; while in the latter are included the phrenic, the lumbar, and 

 the middle sacral arteries. The first three of the visceral branches are single 

 arteries. 



Varieties. Place of division. In more than three-fourths of a considerable number of 

 cases, the aorta divided either upon the fourth, lumbar vertebra, or upon the intervertebral 

 disc below it ; in one case out of nine it was below, and in about one out of eleven above the 

 spot thus indicated : in ten bodies out of every thirteen, the division of the great artery took 

 place within half an inch above or below the level of the iliac crest (R. Quain). An instance 

 of bifurcation immediately below the origin of the right renal artery is recorded by Haller ; 

 and division opposite the second lumbar vertebra has been observed by Boinet, Cruveilhier, 

 and Eckhard. 



Unusual branch. Two remarkable cases are recorded of the existence of a large pulmon- 

 ary branch, which arose from the abdominal aorta close to the coeliac axis, and, after passing 

 upwards through the cesophageal opening in the diaphragm, divided into two branches, which 

 were distributed to the lungs near their bases. 



A. VISCERAL BRANCHES OP THE ABDOMINAL AORTA. 



The coeliac artery or axis (i) is a short wide vessel, usually not more than 

 half an inch in length, which arises from the front of the aorta close to the margin 

 of the opening in the diaphragm. It is directed nearly horizontally forwards at the 

 upper border of the pancreas, being placed behind the small omentum and close to 

 the left side of the Spigelian lobe of the liver. The two semilunar ganglia of the 

 sympathetic are also contiguous to it, one on each side. The artery divides into 

 three branches, viz., the coronary artery of the stomach, the hepatic, and the 

 splenic, which separate simultaneously from the end of the trunk like radii from 

 an axis. 



Varieties. The coeliac axis is occasionally partly covered at its origin by the diaphragm. 

 It may be longer than usual, in which case its branches are not given off together ; or it may 

 be entirely wanting, the coronary, hepatic, and splenic arteries arising separately from the 

 aorta. In some cases the coeliac artery gives off only two branches at its division (the 

 coronary and the splenic), the hepatic being supplied from another source. Rarely, it gives 

 more than three branches to the viscera, the additional vessel being a second coronary, or a 

 separate gastro-duodenal artery. One or both phrenic arteries are frequently derived from 

 this trunk. Cases have been met with in which a connection existed between the coeliac axis 

 and the superior mesenteric artery close to their origin. 



A. The coronary artery of the stomach (iii-iv), the smallest of the three 

 branches derived from the coeliac axis, runs at first upwards and to the left side, in 

 a special fold of the peritoneum, and reaches the cardiac orifice of the stomach. It 

 then turns sharply forwards and downwards, and is continued from left to right 

 along the small curvature of the stomach, distributing branches to both surfaces 



