THE CAT. 



[CHAP. ix. 



posteriorly they meet together and terminate in a single elongated 

 ganglion beneath the tail. 



The filaments which unite the several ganglia with the several 

 spinal nerves are formed partly of white and partly of grey fibres, 

 and the same is the case with the horizontal cords which connect 

 together, on each side, the series of ganglia. The white fibres are 

 deemed to come from the spinal system. 



In the neck, the sympathetic is intimately connected with the 

 pneumogastric . 



The great PLEXUSES of the sympathetic are three in number : one 

 in the thorax, called the cardiac plexus ; one in the abdomen, called 

 the solar plexus. ; and one in the pelvis, called the hypoga&tric plexus. 

 Each is a single, median structure, and each furnishes sympathetic 

 nerves to adjacent viscera. 



The THORACIC PARTS of the gangliated cords, lie on a line with 

 the heads of the ribs, between the pleura and the intercostal vessels. 

 Occasionally two of the ganglia of each side may coalesce. 



The branches given off by the first five or six ganglia go mostly 

 to the aorta and adjacent parts, and are small in size ; but those of 

 the more posterior ganglia join together to form on each side the 

 splanchnic nerve, which penetrates the diaphragm and goes to a 

 special ganglion, called " eemilunar," which is situate in the solar 

 plexus. 



The LUMBAR PARTS of the gangliated cords approach each other, 

 lying on the ventral aspect of the bodies of the vertebrae, along the 

 inner margin of each psoas muscle. In the SACRAL region the cords 

 are much smaller, and they approach each other yet more, uniting 

 together in a single median ganglion (ganglion impar) beneath the tail. 



Of those complex entanglements of nerves and ganglia, the great 

 plexuses, the first, or CARDIAC PLEXUS, lies on the base of the heart 

 and on the aorta and pulmonary artery. It receives the cardiac 

 branches of the pneumogastric nerves, with the cardiac branches from 

 the cervical ganglia of the sympathetic. It constitutes the nervous 

 system of the heart. 



The SOLAR (or EPIGASTRIC) plexus is the largest of all, and lies in 

 the anterior part of the abdomen, between the stomach, aorta, and 

 pillars of the diaphragm, and between the suprarenal capsules. It 

 receives not only the splanchnic nerves, but also some branches from 

 the pneumogastric. It contains several ganglia, the two largest of 

 which are called scmilunar. It gives off very many branches, ac- 

 companying the arteries to the different abdominal viscera. 



The HYPOGASTRIC plexus is that which furnishes sympathetic 

 branches to the pelvis, and lies between the right and left iliac arteries. 

 It receives branches from the lumbar part of the gangliated cords, 

 and from the plexuses in front. Unlike the solar plexus, this one 

 contains no ganglia. It sends backwards two prolongations, one on 

 each side of the pelvic viscera, these prolongations forming what is 

 specially called the pelvic plexus, nerves of which are spread about 

 the pelvic viscera, especially the bladder and generative organs. 



