THE CENTRAL NERVE SYSTEM 



347 



FIG. 124 



WHITE VENTRAL COMMISSURE 



FIGS. 122, 123, and 124. Sections of the spinal cord at the level of the 

 sixth cervical, sixth thoracic, and third lumbar segments, the conducting 

 tracts being indicated on the right side of each section: C. Comma tract 

 of Schultze. //. Olivospinal tract of Helweg. M. Marginal tract of Spitzka- 

 Lissauer. O. Oval field of Flechsig. 



or margins of the foramen magnum and extends to 

 the lower border of the first lumbar vertebra below, 

 from which point it is continued as a narrow thread 

 of gray substance, the filium terminalis. The spinal 

 cord is 18 to 20 inches in length, and weighs one 

 ounce/ 



The columns of the spinal cord are divided into three 

 chief columns or funiculi. The ventral, dorsal, and 

 lateral. 



The columns are simply connecting pathways for 

 the transmission of nerve impulses from the brain 

 centres to spinal centres, and contain efferent, afferent, 

 and association fibers. The course and connecting 

 pathways of these nerve fibers within the white 

 substance is seen to consist of numbers of medullated 



