THE FUNCTION'S OF THE CEREBELLUM 453 



fibres ; or (2) by one ascending the moss fibres through the granule 

 cells, and then passing by their bifurcating axon to the dendrites 

 of the cells of Purkinje ; or (3) by the star-shaped cells of the molecular 

 layer and their basket- work round the body of Purkinje's cells. 



The roof yancjlia consist of the nuclei fastigii near the middle line, 

 the nuclei emboliformes situated just dorsal to these, and the nuclei 

 dentati, large crenated capsules of grey matter lying in the middle 

 of each lateral lobe. The cells composing the grey matter of the 

 central nuclei are large and multipolar, resembling those found in 

 the nuclei of motor nerves. 



The cerebellum receives fibres from all the receptor apparatus of 

 the body which can be classed in the proprioceptive system. The 

 greater number of these fibres run directly to the cortex, especially 

 of the vermis, and there is no evidence of the passage of any efferent 

 fibres from the cortex directly to the motor apparatus of the cord. 



The connections of the cerebellum are established by means of 

 its three peduncles, and may be classified as follows : 



AFFERENT TRACTS. INFERIOR PEDUNCLE. By this peduncle 

 afferent fibres pass to the superior vermis : 



(1) From Clarke's column of the same side by the posterior cere- 

 bellar tract. 



(2) From the dorsal column nuclei, viz. the nucleus gracilis and 

 nucleus cuneatus of each side, so that connection is established in 

 this way with the prolongations of the posterior sensory roots which 

 run into the posterior columns of the cord. 



(3) By the internal restiform body from the vestibular division 

 of the eighth nerve, part of the fibres passing through, and perhaps 

 making connections with, Deiters' nucleus. Fibres are also contri- 

 buted from the sensory nucleus of the glossopharyngeal nerve in the 

 medulla. 



(4) A strong band of fibres passes from the inferior olivary body 

 into the opposite cerebellar hemisphere. Atrophy of one side of the 

 cerebellum induces a corresponding atrophy in the opposite olivary 

 body. 



MIDDLE PEDUNCLE. The broad mass of fibres making up these 

 peduncles is partly afferent and partly efferent. Many fibres originate 

 in the cells in the formatio reticularis of the pons, cross the middle 

 line, and pass up into the lateral cerebellar hemisphere of the opposite 

 side. Fibres also pass from the cerebellum to the pons to end round 

 cells in the same region. By this means connection is established 

 between the cerebellar hemispheres and the grey matter of the cortico- 

 pontine fibres passing by the crura cerebri between the pons and 

 the frontal and temporal portions of the cerebral cortex of the opposite 

 side. On account of this connection there is a close association 



