498 ARTERIES. 



This form of aneurism may burst into the peritoneal cavity, or behind the peritoneum, between 

 the layers of the mesentery, or, more rarely, into the duodenum; it rarely extends backwards so 

 as to affect the spine. 



The abdominal aorta has been tied several times, aud although none of the patients perma- 

 nently recovered, still, as one of them lived as long as tc-n days, the possibility of the re-estab- 

 lishment of the circulation may be considered to be proved. Jn the lower animals this artery is 

 often successfully tied. The vessel may be reached in several ways. In the original operation, 

 performed by Sir A. Cooper, an incision was made in the linea alba, the peritoneum opened in 

 front, the finger carried down amongst the intestines towards the spine, the peritoneum again 

 opened behind, by scratching through the mesentery, and the vessel thus reached. Or either 

 of the operations, described below, for securing the common iliac artery, may, by extending the 

 dissection a sufficient distance upwards, be made use of to expose the aorta. The chief difficulty 

 in the dead subject consists in isolating the artery, in consequence of its great depth; but in the 

 living subject, the embarrassment resulting from the proximity of the aneurismal tumor, and the 

 great probability of disease in the vessel itself, add to the dangers and difficulties of this formida- 

 ble operation so greatly, that it is very doubtful whether it ought ever to be performed. 



The collateral circulation would be carried on by the anastomosis between the internal mam- 

 mary and the epigastric ; by the free communication between the superior and inferior mesen- 

 teries, if the ligature were placed above the latter vessel ; or by the anastomosis between the 

 inferior mesenteric and the internal pudic, when (as is more common) the point of ligature is 

 below the origin of the inferior mesenteric ; and possibly by the anastomoses of the lumbar arte- 

 ries with the branches of the internal iliac. 



The circulation through the abdominal aorta may be commanded, in thin persons, by firm pres- 

 sure with the fingers. Mr. Lister has invented a tourniquet for this purpose, which is of the 

 greatest use in amputation at the hip joint, and some other operations. 



BRANCHES OF THE ABDOMINAL AORTA. 



Phrenic. 



{Gastric. Renal. 



Hepatic. Spermatic. 



Splenic. Inferior mesenteric. 



Superior mesenteric. Lumbar. 



Suprarenal. Sacra media. 



The branches may be divided into sets: 1. Those supplying the viscera. 2. 

 Those distributed to the walls of the abdomen. 



Visceral Branches. Parietal Branches. 



{Gastric. Phrenic. 



Hepatic. Lumbar. 



Splenic, Sacra media. 



Superior mesenteric. 

 Inferior mesenteric. 

 Suprarenal. Renal. Spermatic. 



CCELIAC Axis. (Fig. 290.) 



To expose this artery, raise the liver, draw down the stomach, and then tear through the laj 

 of the lesser omentum. 



The Cceliac Axis is a short thick trunk, about half an inch in length, which 

 arises from the aorta, opposite the margin of the Diaphragm, and passing nearly 

 horizontally forwards (in the erect posture), divides into three large branches, 

 the gastric, hepatic, and splenic, occasionally giving off one of the phrenic 

 arteries. 



Relations. It is covered by the lesser omentum. On the right side, it is in 

 relation with the right scmilmmr ganglion, and the lobus Spigelii : on the left 

 side, with the left semilunar ganglion and cardiac end of the stomach. Below, 

 it rests upon the upper border of the pancreas. 



The Gastric Artery ((hmnaria Ventricnli}, the smallest of the three branche 

 of the coeliac axis, passes upwards and to the left side, to the cardiac orifice of 

 the stomach, distributing branches to the oesophagus, which anastomose with 

 the aortic cesophageal arteries; others supply the cardiac end of the stomach, 

 inosculating with brunches of the splenic artery: it then passes from left to 



