VlscKKAI. 1'LKXrsKS OF SYMPATHETIC. 319 



The aortic plexus is an open network of nerves covering the aorta Aortic 

 below the superior mesenteric artery ; it is stronger on the sides plexus ' 

 than on the front of the aorta, in consequence of its receiving acces- 

 sor}- branches from the lumbar ganglia, especially the left. Above, 

 the plexus derives an offset, on each side of the aorta, from the solar 

 and renal plexuses. It ends below, on each side, in branches which offsets, 

 cross the common iliac artery, and enter the hypogastric plexus. 

 From it offsets are furnished to the spermatic and inferior mesenteric 

 arteries. 



The spermatic plexus, formed by roots from both the aortic and the Spermatic 

 renal plexus, runs on the spermatic artery to the testicle ; in the cord p 

 it joins other filaments on the vas deferens. 



In the female, the nerves on the ovarian (spermatic) artery are in female, 

 furnished to the ovary and the uterus. 



The inferior mesenteric plexus supplies the part of the intestinal ^ferior 

 tube to which its artery is distributed. This plexus is furnished 

 from the left side of the aortic plexus ; and the nerves composing 

 it are whiter and larger than in either of the preceding plexuses of 

 the sympathetic. Xear the colon the branching of the nerves and nerves join 

 the union of contiguous twigs are well marked. Its offsets (plexuses) 



are left colic, sigmoid, and superior hsemorrhoidal : thev ramify on secondary 



. I. -> i plexuses. 



those arteries, and have a like distribution. 



The hypogastric plexus, or the large prevertebral centre for the Hypogastric 

 upply of sympathetic nerves to the viscera of the pelvis, is situate P exu-s: 

 in front of the last lumbar vertebra. It is formed by the union of situation ; 

 the prolongations of the aortic plexus ; and the nerves composing it formation ; 

 are of large size, and interlace in a dense flattened mass, without any 

 interspersed ganglia. Below, the plexus divides into two portions, and ending. 

 right and left, which are continued downwards on the inner side of 

 internal iliac vessels to the pelvic plexuses. 



RELATIONS OF AORTA AND VENA CAVA. 



Before any of the viscera are removed from the body, the relations 

 of the abdominal aorta and vena cava may be learnt. 



Dissection. To see the aorta above the origin of the superior Dissection 

 mesenteric artery, it will be necessary to detach the great omentum 

 from the stomach, without injuring the gastro-epiploi'c arteries along 

 the great curvature ; and after raising the stomach, to remove the 

 peritoneum from the gastric surface of the pancreas. A short arterial 

 trunk (coeliac axis) above the pancreas is not to be quite cleaned now, 

 otherwise the nerves about it would be destroyed. 



The vena cava on the right side of the aorta may be followed up and vena 

 as far as the liver, where it disappears, by separating the transverse 

 colon from the duodenum and by carefully lifting up the outer part 

 of the duodenum ; where the latter lies over the inner part of the 

 right kidney, the confluence of the renal vein and the inferior vena 

 cava will be exposed. Care must be taken however not to injure the 

 duodenum and the adjacent head of the pancreas. The relations of 



