758 



THE CENTRAL AXIS OF TEE NERVOUS SYSTEM. 



the motor nerve-roots ; while a third— the lateral or intermediate— thicker than 

 the others, is confounded superficially with the inferior, and formed by all that 

 portion of the cord situated between the lines of origin of the superior and 



Ca^^ 



TRANSVERSE SECTION OF THE SPINAL CORD IN THE LUMBAR REaiON. (AFTER DEITERS.) 



R.a., Inferior root; R.p., superior root; R.i.p., internal portion of the superior root; C.p., superior 

 conomissure ; C.a.a., inferior commissure ; C.c, central canal. The networlc of myeline fibres 

 in the grey substance, as well as those in the inferior grey commissure, are not indicated. 



inferior roots. Of these three columns, the first is sensory 

 which in reality are only one — are not.^ 



the other two — 



' The existence of so-calleil "systematic lesions" in Man has led anthropotomists to dis- 

 tinguish, in the wliite substance of the cord, a great number of regions. Thus, the innermost 

 portion of the anterior column (inferior in animals) is designated Tiirck's fascicvlus ; the corre- 

 sponding [portion of the pobterior column (superior) in tiie cervical region is GoU'» column ; tlie 

 lateral column is rigoroiisly limited by the grey cornua; while the regions around these latter 

 «re named the anterior and posterior radicular zonex. 



In adhering to the facts of normal anatomy, it must be admitted that some of these dis- 

 tinctions are in great part artificial. Nevertheless, there are found on the limits of certain 



