CHAPTER XXX. 



THE SPINAL CORD. 

 BY J. GERLACH, 



OF ERLANGEN. 



THAT portion of the central nervous system which occupies 

 the greater part of the vertebral canal, the spinal cord, forms 

 a cylindrical column, chiefly composed of nervous tissue, and 

 terminates in the adult with a conical extremity at the level 

 of the first lumbar vertebra. This column presents swellings 

 of considerable size at the points corresponding to the origin 

 of the nerves both of the upper and lower extremities, and 

 consists of two substances, of which the peripheric is white, 

 whilst the central is of a grey colour. 



The outer white substance has long been held to be divisible 

 into three pairs of columns, separated from one another by the 

 anterior longitudinal fissure, by the line of emergence of the 

 anterior and of the posterior roots of the spinal nerves, and 

 by the posterior longitudinal fissure. This division into anterior, 

 lateral, and posterior columns is very distinctly marked on the 

 surface of the spinal cord, but is gradually lost as we pass 

 towards the central grey substance. Besides these six columns, 

 the anterior white commissure, which is situated in front of 

 the grey commissure (fig. 217,/), at the bottom of the anterior 

 longitudinal fissure, has of late years been distinguished as a 

 special constituent of the white substance. 



The central grey substance of the spinal cord, when seen in 

 transverse section, resembles a capital H, and is divided into a 

 central portion, the grey commissure, with the central canal 

 (fig. 217, ig k) ; and into two lateral portions, the anterior half 



