758 



THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 



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

 the others, is confounded supei-ficially with the inferior, and formed by all that 

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



COAi- 



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

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

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

 in the grey substance, as well as those in the infei'ior grey commissure, are not indicated. 



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

 which in reaUty are only one — are not.^ 



the other two- 



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

 tinguish, iu the white substance of the cord, a great number of regions. Thus, the innermost 

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

 sponding portion of the posterior column (superior) in tiie cervical region is GolVs column ; the 

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

 are named the anterior and posterior radicular zones. 



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 



