CH. XLVII.] CONNECTIONS OF THE CEREBELLUM 685 



first cell-station on the cerebellar path. One of these is represented 

 as giving origin to a fibre of the direct cerebellar tract (D.C.T.), which 

 enters the cerebellum by its inferior peduncle. The other cell of 

 Clarke's column is shown giving origin to a fibre of Gowers' tract 

 (G.T.) ; it is represented as making a sharp turn after having reached 

 its highest point, and enters the cerebellum by its superior peduncle ; 

 both of these spino-cerebellar tracts (coloured blue in the diagram) 

 terminate in the cortex of the vermis ; but only a small proportion 

 of their fibres take the roundabout path by the superior peduncle 

 (see p. 658). 



Coming next to the middle peduncle, we see one of its fibres 

 (M.P.) arising from a cell of the nucleus pontis, and crossing the 

 middle line to terminate in the cortex of the opposite cerebellar 

 hemisphere ; entering the nucleus pontis, we see one of the cortico- 

 pontine fibres from the cerebrum The arrows indicate that this is 

 the path (coloured red in diagram) by which impulses reach the 

 cerebellum from the cortex of the cerebrum. The fibres from the 

 cerebrum to the nucleus pontis come in large measure from 

 the frontal lobe (see next chapter). 



The superior peduncle is more complicated, p is one of the cells 

 of Purkinje in the cortex cerebelli ; its axon passes to the nucleus 

 dentatus of the cerebellum ; from the cells of the nucleus dentatus 

 fresh axons carry on the impulse to the optic thalamus of the opposite 

 side ; one of these fibres (S.P.) is shown. From the optic thalamus a 

 fresh relay continues the impulse to the cortex cerebri. Each fibre 

 of the superior peduncle, after it has crossed the middle line (oo), gives 

 off a descending branch (D.), the destination of which is uncertain ; it 

 also gives off branches to the red nucleus ; from the cells of the red 

 nucleus the fibres of Monakow's bundle (M.B.) continues the impulse 

 down to the anterior horn-cells of the opposite side ; owing to the 

 double crossing the cerebellar hemisphere is thus brought into connec- 

 tion with the same side of the spinal cord. 



