STRUCTURE OF THE SPINAL CORD 363 



(cells of the columns). All the motor fibres in the nerve-roots arise 

 from cells in the spinal cord near the point of origin of the root. 

 Any direct influence of the brain on the motor mechanisms of the 

 body is therefore effected through the intermediation of the seg- 

 mental neural mechanisms of the grey matter of the cord. We will 

 consider the function and related structure of the cord in these two 

 aspects : first, as a reflex centre, and, secondly, as a conductor of 

 impulses to the higher parts of the central nervous system 



