HYPOGASTRIC PLEXUS— PELVIC PLEXUSES 837 



massed along the sides of tlio abdominal aorta, and are connected by coniniuni- 

 cating branches which ])ass across the front of the great vesseL It is formed 

 mainly by the downward continuation of the solar plexus, but receives strong rein- 

 forcements from the upper three lumbar ganglia. It gives off the spermatic and 

 inferior mesenteric jilexuses, and terminates below in strong branches to the hj^po- 

 gastric plexus. 



The inferior mesenteric plexus is much smaller than the superior mesenteric 

 plexus, but, like the; latter, is remarkable for its whitish colour. It is derived 

 from the aortic plexus, and is conveyed by the branches of the inferior mesenteric 

 artery to the descending colon, the sigmoid flexure, and to the upper part of the 

 rectum. In the latter situation it communicates Avith the pelvic plexuses. It 

 contains the inferior mesenteric ganglion. 



The spermatic plexus is derived from the aortic and renal plexuses. It ac- 

 companies the spermatic artery as far as the internal abdominal ring, Avhere it is 

 joined l)y a fine plexus derived from the pelvic plexus and accompanying the vas 

 deferens. Thus reinforced, it is conducted by the spermatic cord to the testicle. 



In the female it accompanies the ovarian vessels to the ovary and uterus. 



The more important fibres which pass to the solar plexus have already been 

 described in connection with the lumbar and dorsal portions of the sympathetic cord. 



HYPOGASTRIC PLEXUS 



From the lower ganglia of the lumbar sympathetic cord, two or three strong 

 branches ])roceed which cross oblicjuely in front of the connnon iliac arteries. 

 These nerves are joined by stout offsets from the aortic plexus, and interlace in 

 front of the body of the fifth lumljar vertebra with the corresponding nerves of the 

 opposite side to form a broad flattened band, Avhich is termed the hypogastric 

 plexus. This plexus is remarkable in that it contains little or no ganglionic 

 matter. It soon divides into two lateral portions, the pelvic or inferior hypogastric 

 plexuses. 



Pelvic Plexuses 



Each of the two lateral continuations of the hypogastric plexus contains gan- 

 glion cells; it passes downwards on the side of the rectum, where it is joined hy 

 slenfier branches from the sacral part of the gangliated cord, and by branches from 

 the third and fourth (sometimes the second) sacral nerves. In this manner the 

 pelvic plexuses are formed. Each pelvic plexus gives off branches to the pelvic 

 viscera; these branches, in the greater part of their course, follow the arteries of 

 the ])elvis. We distinguish middle hsemorrhoidal, vesical, prostatic, and (in the 

 female) vaginal and uterine jilexuses. 



The middle haemorrhoidal plexuses form a closely-meshed expansion on the 

 sides of the rectum; they comnmnicate above with branches from the inferior 

 mesenteric plexus, and below with the inferior haemorrhoidal branches of the pudic 

 nerve. • 



The vesical plexus is clneily formed by fil)res derived from the third and fourth 

 sacral nerves. The nerves pass forwards on each side of the l)ladder, and divide 

 into two groups — a superior group, which sup])lies the up])er two-thirds of the 

 bladder; and an inferior group, which is distributed to the lower third of that 

 viscus. In the male, braiichc^s are given off to the vesicula^ seminales and vasa 

 deferentia. The nerves to the vas deferens form a slender plexus which accom- 

 panies that structure as far as the internal abdominal ring, where it unites with the 

 spermatic plexus. 



The prostatic plexus is placed a little lower down than the vesical plexus, of 

 which it is in some measure a continuation. The nerves which pass to it are 

 of relatively large size, and are massed on the sides of the organ, where several 

 ganglionic masses, from one-eighth to a quarter of an inch in length (ganglia 

 prostatica of Miiller), are developed. From the prostatic ))lexus, oft'sets are 

 furnished to the vesicuhe seminales, and also branches to the erectile structures of 

 the penis; the latter l)ranches are called cavernous nerves. 



