CHAP1 ER CI 



THE AUTONOMIC NERVOl - SYSTEM 



In discussing the physiology of the central oervou I m, we hi 



broken away from the traditional text! k treatment of the Bubject in 



that we have lefl practically untouched any description of the 



various nerve tracts or of the position of the nerv nters. Wi 



pursued this policy in the belief thai the study of tl ture 



belongs just as surely to the anatomisl as does the structui 



of the body, notwithstanding that to trace the course of ,: ath- 



ways he may have to call to his aid the physiologist and clinical ne 



There is one part of the nervous Bystem, however -namely, the involuntary 



or autonomics] the physiology of which it is impossible to discuss a] 



from its anatomy, because this lias depended very largely on physiological 



methods for its elucidation. Until such methods were emphasized and 



while anatomy alone was depended upon, little could be learned 



functions and connections of the sympathetic chain and of the varii 



nerve plexus thai compose the involuntary nervous Bystem. v. 



review briefly the general anatomical plan of this Bystem ;is described by 



Ga shell. 17 



GENERAL PLAN OF CONSTRUCTION 



The plan of the involuntary nervous m is much the Bam< 



of the voluntary, the main points of difference being dependenl upon the 

 location of the neurons composing the reflt It u ill be remembered 



that there ate three of these: the receptor, the internuncio! 



lector neurons (page 782). The receptor neurons have the - 



for both systems; Qamely, the posterior root ganglia F 3 Tic- it 



nuneial neurons of the involuntary system, lik< 



have their cella in the spinal cord, where the d. in 



thoracic region, by the cella of the lateral horn ol 



sacral region, bj a similarly pla 1 collection of cells; and in the bul 



region, mainly by the dorsal nucleus of the rhe m 



tlu^ difference between the two systems is dependenl o 

 fibers of the internuncial neurons, in tin- involunl 

 spinal cord befon connecting with the eff< 

 are contained in the various ganglii 



