318 THE AX ATOMY OF THE HORSE. 



right sac; while the superior, after giving branches to the left sac, 

 joins the solar plexus. 



The Splanchnic Nerves. On each side there are two splanchnic 

 nerves — a great and a small Both are formed by efferent branches of 

 the dorsal portion of the sympathetic gangliated cord, and they reach 

 the abdomen by passing between the diaphragm and the psoas parvus 

 muscle. The great splanchnic nerves terminate in the semilunar 

 ganglia; the small nerves pass directly to the solar plexus, or they may 

 be continued to the renal or the suprarenal plexus. 



The Semilunar Ganglia are the largest in the body. They are 

 placed one at each side of the lower face of the aorta, between the 

 coeliac and anterior mesenteric arteries. Each receives the great 

 splanchnic nerve of its own side, and the two ganglia communicate by 

 transverse branches across the lower face of the aorta. The efferent 

 branches which proceed from them form the solar plexus. 



The Solar Plexus is an intricate network of nerves and ganglia. It is 

 joined on each side by the lesser splanchnic nerve, and by the terminal fila- 

 ments of the superior oesophageal nerve. From the plexus nerves pass to 

 the abominal viscera, and in doing so they run in company with arteries. 

 There is thus : a coeliac plexus, whose branches i-each the liver, pancreas, 

 spleen, and stomach, by accompanying the divisions of the hepatic, 

 splenic, and gastric arteries ; a renal and a suprarenal plexus, which pass 

 to the kidneys and suprarenal bodies ; an aortic j^l^xus, continued back- 

 wards on the aorta to join the posterior mesenteric plexus; and an 

 anterior mesenteric plexus, already described. 



Directions. — The form, situation, and relations of the kidneys, and the 

 coiirse of the ureters should now be examined. AVithout displacing the 

 kidneys, the fat and })eritoneum is to be stripped from their lower face, 

 their vessels being carefully cleaned at the same time. The ureter will 

 be found ])assing backwards from the notched inner border of each 

 kidne}', and it is to be followed backwards to the entrance to the pelvis. 

 In close relation to each kidney is its suprarenal body, which, to prevent 

 displacement, may be transfixed in position with a long pin. 



The Kidneys (Plates 44 and 47) are the two glandular bodies that 

 secrete the urine. Each kidney occupies a position at the side of the 

 vertebral column, on the inferior aspect of the loins, and at the roof of the 

 abdominal cavity. In all except the most emaciated subjects, the kidneys 

 are surrounded by a (piantity of adipose tissue, which is so abundant in 

 fat animals as to completely isolate them from surrounding objects. The 

 most common shape of the mammalian kidney is so well known that it is 

 popularly used as a descriptive term, objects having a similar form being 

 described as "kidney-shaped." Each kidney possesses two surfaces, two 

 borders, and two extremities. The inferior surface is convex ; the 

 superior, which is concealed at present, is almost flat. The outer border 



