346 THE GKEAT SYMPATHETIC. 



way to the ganglion of the sympathetic, passes over and through it, its 

 fibres conjoining themselves with gray ones, which they have gathered in 

 the ganglion. The gray or gelatinous root is to "be viewed as having its 

 origin in the ganglion of the sympathetic, and ^sending its fibres chiefly 

 to the ganglion on the posterior root of the spinal nerve, but few of them 

 doubtfully communicating with the anterior root. The fibres which seem 

 to enter the cord are probably for the supply of blood-vessels. Each of 

 these sympathetic ganglia is, therefore, a nervous centre, sending forth 

 strands in three directions : 1st. To join the spinal fibres in their distri- 

 bution ; 2d. To the spinal cord itself, or chiefly to the ganglia on the pos- 

 terior roots of its nerves ; 3d. To the next sympathetic ganglion above. 

 Sympathetic In the various plexuses of the sympathetic, vesicles are found, 

 plexuses. f rom w hi cn g^y fibres seem to originate. The branches which 

 supply the viscera constantly form plexuses ; the arteries are surrounded 

 with such a net-work. The splanchnic ganglia, with their interconnect- 

 ing strands, and supplies from the cerebro-spinal, give rise to four great 

 plexuses: the pharyngeal, the cardiac, the solar, and the hypogastric. 

 The first and last of these are in symmetrical pairs ; the other two are 

 single, and placed on the median line. 



From its construction the sympathetic can not be regarded as an iso- 

 Ph -sical effects ^ ate ^ or self-acting system, since all its branches contain 

 of sympathetic fibres derived from the cerebro-spinal. In function it must 

 therefore be adjuvant to that system, and it must be admit- 

 ted that the motor and sensory qualities of the included spinal fibres, ac- 

 cording as they have been derived from the anterior or posterior columns 

 of the cord, are continued in their association with the sympathetic. 

 Hence, in so far as being a compound nerve, it possesses both those func- 

 tions, and this conclusion is corroborated by such facts as those of the 

 distribution of the sympathetic both to muscular portions, as to the heart, 

 and also to sensitive ones ; by the circumstance that the intestinal canal 

 from the stomach to the end of the colon receives its nervous supply 

 from this source alone. Experiments on the sympathetic ganglia estab- 

 lish a similar conclusion, irritation of the cceliac ganglion, for instance, 

 giving rise to increased peristaltic motions, and pathological observations 

 furnishing like evidence as regards the sensory function. Compared 

 with other nerve trunks, the sympathetic is much less active in these re- 

 spects, a high irritation of the parts supplied by it often being required 

 to cause pain, and, in like manner, its motor fibres are little under the in- 

 fluence of the will. 



The sympathetic transmits sensations so tardily that it has been sup- 

 posed that one office of its ganglia is for the purpose of cutting off such 

 impressions ; and, in like manner, when motor fibres of the cerebro-spi- 

 nal system pass through its ganglia, their conducting power appears to 



