702 THE SYMPATHETIC NERVES. 



ramifies on the branches of the vena portee and the hepatic artery. Offsets from the 

 left pneu mo -gastric and diaphragmatic nerves join the hepatic plexus at the left 

 side of the vessels. From this plexus filaments are furnished to the right supra- 

 renal plexus, as well as other secondary plexuses which follow the branches of the 

 hepatic artery. Thus there is a cystic plexus to the gall-bladder; and there are 

 pylorie, gastro-epiploic, and gastro- duodenal plexuses, which unite with coronary, 

 splenic, and mesenteric nerves. 



The splenic plexus, continued on the splenic artery and its branches into the 

 substance of the spleen, is reinforced at its beginning by branches from the left semi- 

 lunar ganglion, and by a filament from the right vagus nerve. It furnishes the left 

 gastro-epiploic and pancreatic plexuses, which course along the corresponding branches 

 of the splenic artery, and, like the vessals, are distributed to the stomach and 

 pancreas. 



SUPERIOR MESENTERIC PLEXUS. The plexus accompanying the superior mesenteric 

 artery, whiter in colour and firmer than either of the preceding offsets of the solar 

 plexus, envelopes the artery in a membraniform sheath, and receives a prolongation 

 from the junction of the right pneumo-gastric nerve with the cceliac plexus. Near 

 the root of the artery, ganglionic masses (gangl. ineseraica) occur in connection with 

 the nerves of this plexus. 



The offsets of the plexus are in name and distribution the same as the vessels. 

 In their progress to the intestine some of the nerves quit the arteries which first sup- 

 ported them, and are directed forwards in the intervals between the vessels. As they 

 proceed, they divide, and unite with lateral branches, like the arteries, but without 

 the same regularity : they finally pass upon the intestine along the line of attachment 

 of the mesentery. 



THE AORTIC PLEXUS. 



The aortic or intermesentcric plexus, placed along the abdominal aorta, 

 and occupying the interval between the origin of the superior and inferior 

 mesenteric arteries, consists, for the most part, of two lateral portions, 

 connected with the ^emilimar ganglia and renal plexuse?, which are extended 

 on the sides of the aorta, and which meet in several larger communicating 

 branches over the middle of that vessel. It is joined by branches from some 

 of the lumbar ganglia, and presents not unfrequently one or more distinct 

 ganglionic enlargements towards its centre. 



The aortic plexus furnishes the inferior mesenteric plexus and part of the 

 spermatic, gives some filaments to the lower vena cava, and ends below in 

 the hypogastric plexus. 



INFERIOR MESENTERIC PLEXUS. This plexus is derived principally from the left 

 lateral part of the aortic plexus, and closely surrounds with a network the inferior 

 meeenteric artery. It distributes nerves to the left or descending part and the 

 sigmoid flexure of the colon, and assists in supplying the rectum. The nerves of this 

 plexus, like those of the superior mesenteric plexus, are firm in texture, and of a 

 whitish colour. 



The highest branches (those on the left colic artery) are connected with the last 

 branches (middle colic) of the superior mesenteric plexus, while others in the pelvis 

 unite with offsets derived from the pelvic plexus. 



HYPOGASTRIC PLEXUS. 



The hypogastric plexus, the assemblage of nerves destined for the supply 

 of the viscera of the pelvis, lies invested in a sheath of dense connective 

 tissue, in the interval between the tyvo common iliac arteries. It is formed 

 by eight or ten nerves on each side, which descend from the aortic plexus, 

 receiving considerable branches from the lumbar ganglia, and, after crossing 

 the common iliac artery, interlace in tho form of a flat plexiform mass 

 placed in front of the lowest lumbar vertebra. The plexus contains no 



