VIII 



THE HIND-BRAIN 



429 



The efferent cerebello-spinal fibres that leave by the lower 

 cerebral peduncle are represented by the direct ventro-lateral 

 bundle of Marchi, the course of 

 which has been well illustrated 

 by Thomas. The fibres of this 

 bundle pass through the inner 

 segment of the corpus restiforme 

 between the cells of Bechterew's 



Fin. 228. Plan of olivo-cerebellar paths, a; 

 cerebello - olivary, b ; cerebello - spinal, 

 crossed, <; <l, and direct, e, which accompany 

 the pyramidal tracts. (Mingazzini.) 



Fie. 229. Plan of direct sensory cerebellar 

 paths (Edinger), running froTii Deiters' D, 

 and Bechterew's 7J, nucleus of vestibularis v, 

 to nucleus fastigii t, and nucleus globosus g. 



and Deiters' nuclei, run through the formatio reticularis in the 

 neighbourhood of the inferior olive, and pass into the ventro- 

 lateral marginal zone of the cord without decussation. After 

 unilateral extirpation of the cerebellum there is descending 

 degeneration of this bundle, as far as the lumbar region, which 

 decreases from above downwards (Fig. 230). 



C 



FIG, 230. Sections of spinal cord. A, lumbar; B, thoracic; C, cervical, after extirpation of right 

 half of cerebellum in dog. Showing degeneration of Marchi's antero-lateral tract on same side 

 as the extirpation. <i, efferent spino-cerebellar bundle degenerated on right side as far as the 

 lumbar section, while on the left side the degeneration is slight, partial, and does not extend 

 beyond the cervical section. The bundle thus includes nearly the whole border of the ventro- 

 lateial eiilumn ; at '/ it takes in part of the pyramidal tract; at c it comprises the area 

 in which lies the anterior portion of Flechsig's cerebellar tract; at d some fibres of the 

 ventral roots are also degenerated. 



It seems probable from the observations of Thomas that 

 Marchi's bundle springs, like the fibres of the superior cerebellar 

 peduncle, from the dentate nucleus, and that the degeneration of 



