CH. XLV.] 



ROOTS OF THE SPINAL NERVES 



653 



These are omitted from the diagram to avoid confusion (see, 

 however, fig. 185, p. 190). 



A fibre of the posterior root is also shown ; this originates from 

 the cell G of a spinal ganglion ; the process of this cell bifurcates, 

 one branch (B) passing to the periphery, where it ends in an arbor- 

 escence in the skin (S) ; the arrow by the side of this branch 

 represents the direction of conduction of the sensory impulses from 

 the skin. An arrow in the opposite direction would indicate the 

 direction of its growth. The other branch (C) passes into the spinal 



FIG. 401. Course of nerve-fibres in spinal cord. (After Sch.afer.) 



cord, where it again bifurcates; the branch E, a short one, passes 

 downwards and ends in an arborisation around one of the small cells 

 (Pj) of the posterior cornu ; from which a new axis-cylinder arises, 

 and terminates around one or more of the multipolar cells (4) of the 

 anterior horn. 



The main division D travels up in the posterior column of the 

 cord, and ends in grey matter at various levels. Some collaterals (5) 

 possibly terminate by arborising directly around the anterior cornual 

 cells, principally of the same side ; others (6) do so with an intermediate 

 cell-station in a posterior cornual cell (P a ) ; others (7) arborise around 

 the cells of Clarke's column (C) in the thoracic region of the cord, 



