408 ABDOMIXAL AORTA. 



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 cap- 

 sular, the renal, and the spermatic arteries ; whilst in the latter are included 

 the phrenic, the lumbar, and the middle sacral arteries. The first three of 

 the visceral branches are single arteries. 



PECULIARITIES. Point 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 of nine it was below, and in about one 

 of eleven above the spot thus indicated. In ten bodies out of every thirteen, the divi- 

 sion of the great artery took place within half an inch above or below the level of the 

 iliac crest; and it occurred more frequently below than above the fourth interver- 

 tebral space. (R. Quain, op. cit. p. 415.) An instance of bifurcation immediately 

 below the origin of the right renal artery is recorded by Haller (Disputat. Anatom. 

 t. vi. p. 781). 



Unusual Branch. A. very remarkable case is recorded of the existence of a large 

 pulmonary branch which arose from the abdominal aorta, close to the coeliac artery, 

 and after passing upwards through the oesophageal opening in the diaphragm, divided 

 into two branches, which were distributed to the lungs near their bases. (Referred to 

 by R. Quain in his work " On the Arteries," p. 416.) 



A. VISCERAL BRANCHES OF THE ABDOMINAL AORTA. 



I. CCELIAC ARTERY OR AXIS. 



The cceliac artery, a short arid wide vessel, arises from the aorta close 

 to the margin of the diaphragm. It is directed forwards nearly horizon- 

 tally, and is not more than half an inch long. It is behind the small 

 omentum, and lies close to the left side of the lobulus Spigelii of the liver, 

 and above the pancreas, the two semilunar ganglia being contiguous to it, 

 one on each side. This artery divides into three branches, viz.., the coro- 

 nary artery of the stomach, the hepatic and the splenic, which separate 

 simultaneously JFrom the end of the artery like radii from an axis. 



PECULIARITIES. 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. ttarely, 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 sometimes 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. 



Fig. 283. THE" ARTERIES OP THE STOMACH, LIVER, AND OMENTUM 

 (from Tiedemann). | 



The liver is turned up so as to show its lower surface with the transverse fissure or 

 porta, and the vessels and ducts entering it. a, the right lobe of the liver; 6, the left 

 lobe; c, the gall-bladder; c', the biliary or hepatic ducts; c", the ductus coramunis 

 choledochns ; d, the front of the antero-posterior fissure and the round ligament ; e, the 

 cardiac orifice of the stomach ; f, on the great curvature of the stomach near its cardiac 

 end, points to the spleen ; </, the pylorus ; 7t, the duodenum ; i, the great omentum ; k, 

 some of the small intestines in the lower part of the abdomen ; 1, upon the trunk of the 

 abdominal aorta, below the root of the inferior phrenic arteries, and above the coeliac 

 axis ; 2, placed on the meeting of the crura of the diaphragm, the coronary artery of the 

 stomach ; 2', the same artery proceeding round the small curvature of the stomach and 

 ending by anastomosis with the superior pyloric ; 3, the main hepatic artery, continued 



