THE N-ERVOUS SYSTEM OF MAN. 



59 



cm> 



up a posterior column to the thalamus, communicating 

 with a sensory cell of that ganglion, and thence onward 

 to a sensory cell of the 

 cerebral cortex, awaken- 

 ing consciousness there ; 

 then the impression is 

 transferred to a motor cell 

 of the cerebral cortex, 

 which sends it on in the 

 form of will down through 

 a motor cell of the corpus 

 striatum, then down a fiber 

 of an anterior column of 

 the cord, and, after com- 

 municating with a spinal 

 motor cell, out by an an- 

 terior root and a spinal 

 nerve, to terminate in a 

 muscle and cause contrac- 

 tion there. 



In the reflex system 

 the course is the same, ex- 

 cept that the impression 



Carried up by the Sensory Flc - 37-— Diagram of brain, thalamus- 



. . ,, • corpus, and a portion of spinal cord, 



fiber "snort Circuits across representing: course of transmission 



r_„„, ti,„ „„•„„! ,, °f nerve influence: cs, cerebral sen- 



from the Spinal sensory sory, and ««, cerebral motor cells ; 



Cell to the Spinal motor S P S < s P inal sensory, and spm, spinal 



. motor cells; ss, sensitive surface; 



Cell without going up to m, muscle. The arrows show the 



. i , , direction of transmission. 



the cerebrum to awaken 



consciousness there. The course is shown in the dia- 

 gram (Fig. 37). 



General Mode of Action of the Whole. — Suppose each 

 sensory fiber to have its own terminal, its own spinal 

 sensory cell, and its own cerebral sensory cell, and each 

 motor fiber to have its own muscular fiber terminal, its 



