272 SPECIAL PHYSIOLOGY. 



ered. The anterior or motor roots of the spinal nerves proceed from 

 fibres, which, as already mentioned, may be followed through the ante- 

 rior cornu of the gray matter of the cord ; some pass upwards and 

 downwards into the anterior and lateral columns ; others come into 

 relation, in the gray matter, with the fibres of the posterior roots of 

 the same side ; whilst another set cross over to the opposite side of the 

 cord, decussating there with fibres coming in the other direction, and 

 ending in the anterior and lateral columns of that side, or even in the 

 anterior roots of its nerves ; many come into close connection, or are 

 continuous, with the posterior roots of the same side ; and, finally, 

 many end in the gray matter, where they become connected with the 

 multipolar cells. These fibres, like those of the posterior roots, resolve 

 themselves into proper fibres of origin in the cord, fibres of association 

 of the nerves of the same and opposite sides, and longitudinal fibres, 

 which probably connect the nerves directly with the encephalon. 



The path of the voluntary motorial stimulus appears to be down- 

 wards, through the anterior column and adjacent part of the lateral 

 column of white substance, and perhaps through the anterior cornu 

 and gray matter. When the posterior columns are divided trans- 

 versely, no apparent loss of volitional power takes place. If, however, 

 the anterior and lateral columns be cut across, the parts below are 

 paralyzed, on the same side, as regards voluntary motion. If the sec- 

 tion be made high up in the cord, division of the anterior white col- 

 umns was said, by Bell, to have the same effect ; but Brown-Se'quard 

 maintains, that in this region the lateral columns convey the volitional 

 impulses, the gray matter being also slightly concerned in this act. 

 If the cord be cut completely across, and the cut end of the lower 

 portion, which is detached from the brain, be irritated on the section 

 of its antero-lateral column, convulsive movements will take place in 

 the muscles below ; but if the posterior part of the section be irritated, 

 no movements occur. And it may be added, that if the cut ends of 

 the anterior columns of the part still in connection with the brain, be 

 irritated, no movement takes place ; whereas, if the cut ends of the 

 posterior columns be irritated, pain is produced. 



A most remarkable accident, which occurred to a gendarme in-Paris, 

 has supplied experimental proof of the paths of voluntary motion and 

 sensation, in the human subject. He was struck in the back of the 

 neck by a knife ; his right arm was slightly, and the right half of the 

 trunk and the right leg completely paralyzed, as regards voluntary 

 motion ; whilst sensation was quite perfect in all these parts. He died 

 in four days. The point of the knife was found in the vertebral canal, 

 having passed through the arch of the sixth cervical vertebra on the 

 right side ; it had exactly divided only the anterior column, the lateral 

 column, and the adjacent part of the gray matter on the right side of 

 the spinal cord. 



It remains to notice that, as already observed, the median longitu- 

 dinal section of the cord, in animals, does not destroy voluntary motion. 

 It should also be remarked, that in certain cases of disease of the 

 spinal cord, the posterior columns of the cord have been found disor- 

 ganized, without there having been any impairment of sensation. As 



