THE SPINAL CORD. 



409 



terior horn. Their neuraxes, which originate either from the cell- 

 body or from a dendrite, pass over into the posterior column. The 

 stellate cells are supplied with dendrites, which either branch in 

 the substance of Rolando or extend into the column of Burdach. 



The gray matter contains, further, numerous medullated nerve- 

 fibers, in part the neuraxes of the nerve-cells previously mentioned, 

 and in part collateral and terminal branches of the nerve-fibers of 

 the white matter with their telodendria ; also supporting cells, 

 known as neurogliar cells (to be discussed later), and blood-vessels. 



The white matter of the spinal cord consists of medullated fibers, 

 which are devoid of a neurilemma, of neurogliar tissue, and of fibrous 

 connective tissue. 



In each half of the cord the white substance, which surrounds 

 the gray, is separated by the gray matter and its nerve-roots into 



Posterior horn 

 cell. 



Crossed pyram- 

 idal column. 



Golgi cell of 



posterior horn. 



Direct cerebel- 

 lar column. 

 Column cells. 



Golgi'scommis- 

 sural cells. 



Cowers' 



column. 

 Motor cells. 



Collaterals 

 of crossed 

 pyramidal 

 column. 



Collaterals 

 ending in 

 the gray 

 matter. 



Direct pyramidal column. 



Fig. 328. Schematic diagram of the spinal cord in cross-section after von Lenhos- 

 , showing in the left half the cells of the gray matter, in the right half the collateral 

 tranches ending in the gray matter. 



Xiree main divisions or columns: The first division, lying between 

 the anterior median fissure and the anterior horn, is the anterior 

 column ; the second, lying between the anterior and posterior 

 horns, is the lateral column (since the anterior and lateral 

 columns belong genetically to each other, the term anterolat- 

 eral column is often used) ; and the third, lying between the poste- 

 rior nerve-root and the posterior median septum, is the posterior 

 column. 



By means of certain methods it has been possible to separate 

 the white substance into still smaller divisions, the most important 

 of which may here be described. 



In each anterior column is found a narrow median zone extend- 

 ing along the entire length of the anterior median fissure and con- 



