CONNECTION OF SYMPATHETIC AND SPINAL. 



345 



What are here spoken of as nervous strands are perhaps more correctly 

 prolongations of the ganglia themselves. 



The origin of the sympathetic has been long a subject of dispute, some 

 supposing that it is a special system, of which the ganglia are origin of the 

 so many independent centres, establishing incidental commu- sympathetic, 

 nications with the cerebro-spinal ; others, that its origin is in the internal 

 viscera, and its termination in the cerebro-spinal system, this opinion be- 

 ing supported by the alleged facts that the sympathetic, in its develop- 

 ment, appears before the other parts of the nervous system, and simulta- 

 neously with the splanchnic organs, and that it has been found in mon- 

 sters without a brain or spinal cord ; others, again, suppose that it orig- 

 inates from the roots of the cerebro-spinal system, and terminates in the 

 interior organs. Regarding it in this light, some have imputed its origin 

 to all the spinal, and fifth and sixth cranial conjointly ; others have lim- 

 ited it to the two latter. 



The pneumogastric nerve aids it in forming three of its plexuses, the 

 pharyngeal, cardiac, and solar. In certain respects the pneu- Eelations of 

 mogastric and sympathetic seem to exhibit a reciprocal de- 

 velopment, in some of the lower animals the former pre- pathetic, 

 dominating over, and supplying the place of the latter; and this replace- 

 ment, it is said, goes on in the descending series until, in the cephalopo- 

 dous mollusks, the sympathetic has disappeared, and the pneumogastric 

 takes its place. 



Fig. 175 illustrates the relation 

 of the sympathetic and spinal nerves : 

 c, c, anterior fissure of the spinal 

 cord ; , anterior root of a dorsal 

 spinal nerve ; p, posterior root, with 

 its ganglion ; #', anterior branch ; p' 9 

 posterior branch ; s, sympathetic ; <?, 

 its double junction with the anterior 

 branch of the spinal nerve by a white 

 and a gray filament. 



The sympathetic chain therefore 

 establishes connections Connection of 

 with the cerebro-spinal SfgSfe 

 system. Each spinal tem. 

 nerve is brought into relation with 

 it through two strands, a tubular or 

 white, and a gelatinous or gray. 

 The tubular or white strand may be 

 regarded as actually arising from the 

 spinal cord, and consisting of motor 



Relation of the sympathetic and spinal. an( J Se nSOry filaments. It makes its 



Fiy. 1T5. 



