THE CEREBRUM 



265 



A.O.N 



FIG. 84. Scheme of relationship of cells and fibers of brain and cord. 



(Kirkes.) 



Pyr, cell of Rolandic area; Ax, its axis cylinder crossing the middle line AB, to 

 enter one of the pyramidal tracts; the collateral Call goes to the cortex of the oppo- 

 site hemisphere, while another, str, enters the corpus striatum. The axis cylinder 

 arborizes around an anterior horn cell, whence a motor fiber goes to the muscle. 



The axis cylinder from the spinal ganglion cell is represented as bifurcating and 

 sending one branch to the periphery and one to the cord; the latter itself bifurcates, 

 the lower division ending as shown better in Fig. 77. N.G, cell in posterior cornu of 

 the cord or posterior column of the bulb. The distance of this cell from the point of 

 entrance of the axis cylinder into the cord may be great or small. Note the collat- 

 erals from it in Fig. 77. I.A, decussating fiber ending at cell in optic thalamus, O.T, 

 from which a fiber passes to the cortex. A collateral is shown passing from the 

 ascending sensory fiber to a cell of Clarke's column, whence a fiber passes to a cell, P, 

 of the cerebellum. 



