n6 



HISTOLOGY. 



have become fibrous, but it lodges no nerve cell bodies. It is permeated 

 with the processes of nerve cells, the bodies of which remain within the gray 

 layer, or the spinal ganglia. On the outer surface of the cord there are 

 longitudinal grooves which form the boundaries of certain subdivisions 

 of the white layer. These grooves are the dor so-median sulcus; the 

 dor so-lateral sulcus, along which the dorsal roots enter the cord; the ventro- 

 lateral sulcus, along which the ventral roots leave the cord; and the ventro- 



Dorsal 



median Dorsal 

 Entrance zone, septum, funiculus. 



Median .... 1 Portion of 



>- dorsal 

 Lateral) root. Dorsal root. 



Dorsal column. 



Groups of nerve cells. 



Ventral root. 



Central -canal. 



White Ventral Ventral funiculus. 

 commissure, median 

 fissure. 



FIG. 140. CROSS SECTION' OF THE LUMBAR ENLARGEMENT OF THE HUMAN SPINAL CORD. X 8. 



median fissure, which unlike the others becomes a very deep narrow 

 depression. Between these four grooves the white substance on either 

 side of the cord forms the dorsal, the lateral, and the ventral funiculi. 

 Each dorsal funiculus receives the entering fibers from the dorsal roots 

 on one side of the cord; it represents the oval bundle which has enlarged 

 and been folded in toward the median dorsal line. Later a dorsal median 

 septum becomes more evident separating the two dorsal funiculi. Ven- 



