298 THE NERVOUS SYSTEM 



fiber as passing directly to a cord cell itself. The anterior 

 root is entirely motor except for a degree of "recurrent" 

 sensibility which is due to the presence in it of posterior root 

 fibers which have passed backward from the point of junc- 

 tion of the two probably to supply the membranes of the 

 cord. The common trunk is, of course, mixed, as are the 

 anterior and posterior branches passing from it. 



These spinal nerves are distributed to the muscles of the 

 trunk and ext r emities, to the integument of almost the entire 

 body and to some mucous membranes; and from what has 

 been said in speaking of the cord about the connection be- 

 tween it and these nerves, and their connection through it 

 with the higher centers, it is evident that they are most im- 

 portant factors which, acting under the guidance of the sen- 

 sorium, on the one hand, tell of the condition of the or- 

 ganism its relations and environments and, on the other, 

 control the voluntary movements of the body. 



The spinal nerve fibers come in part directly from the 

 brain and in part from the gray cells of the cord. 



THE SYMPATHETIC SYSTEM. 



The sympathetic has been separated from the cerebro- 

 spinal system only for the sake of convenience. The 

 former sends filaments to the latter and receives both motor 

 and sensory .fibers in return, while the cooperation of the two 

 systems, regulating in harmony all the physiological pro- 

 cesses going on in the body, is too evident to be questioned. 



The sympathetic system is remarkable for the number of 

 ganglia connected with it. These may be divided into (a) 

 those along the vertebral column, as the thoracic, (b) those 

 in close proximity to the viscera and from which those vis- 

 cera are to be directly supplied, as the semilunar, and (r) ter- 

 minal ganglia which the fibers reach just before final distri- 

 bution, as the cardiac, intestinal, etc. The sympathetic is, 

 therefore, frequently known as the ganglionic system. 



