THE CEREBELLAR CORTEX 43 



(6) The descending cerebellar fibres. . These arise from the cortex of the cerebellum and 

 pass down the cord mingled with other fibres in the antero-lateral tract. They end in the 

 median gray matter of the cord. Marchi has shown that these fibres are numerous (2). 



(c) The nuclei gracilis (G) and cuneatus (C) of the medulla on both sides, in which the 

 columns of Goll and Burdach end, send a few fibres to the cerebellum. Those on the 

 right side send fibres directly into the right restiform body and thence to the right hemi- 

 sphere of the cerebellum (3), (4). Those on the left side send fibres across the median line 

 of the medulla in the sensory decussation. These then pass forward in the raphe, pass around 

 the surface of the right pyramid and olivary body (O) and join the restiform body, and thus 

 reach the cerebellum (5), (6). These end partly in the corpus dentatum and partly in the cortex. 



(d) The olivary body (O) and interolivary nuclei of each half of the medulla send a 

 large tract across the median line which enters the inferior peduncle and terminates about 

 the corpus dentatum (7). 



II. The middle peduncle of the cerebellum contains the fibres which make up the great 

 mass of transverse fibres in the pons Varolii. 



(a) There is an important bundle of fibres connecting the nucleus vestibuli of the 

 medulla (in which the portion of the acoustic nerve which comes from the semilunar canals 

 ends) with the cerebellum. These lie deep in the mass of fibres of the middle peduncle, 

 and pass to the cortex and nuclei of the vermiform lobe (8). 



(S) There are some fibres which connect the cerebellar cortex and the fillet as shown by 

 the degenerative method, but in which direction they pass is uncertain, probably upward (9). 



(c) Those fibres which arise from the gray masses of the pons pass outward to the 

 cerebellar cortex. These have close relation with the fibres which descend to the pons from 

 the frontal lobes of the brain and thus make a continuous functional tract between the frontal 

 lobe of each side and the cerebellar hemisphere of the opposite side, the crossing occurring 

 in the pons (10). 



(d) Those fibres which arise from the cortex of the cerebellum pass to the gray masses 

 of the ventral part of the pons, from which many new fibres arise which join the pyramids 

 and pass to the medulla or join the descending fibres which pass into the antero-lateral 

 columns of the cord. Some of these fibres decussate in the pons, but the majority end on 

 the side from which they arise (u). 



III. The superior cerebellar peduncle contains two sets of fibres passing in opposite 

 directions between the corpus dentatum and the red nuclei of the tegmentum (12), (13). The 

 majority of these decussate under the corpora quadrigemina, but all do not, hence each corpus 

 dentatum is connected with both red nuclei. 



