THE CEREBELLUM. 



The Projection System. The fibers composing this system con- 

 nect the cerebellar cortex with certain structures in the cerebrum, 

 pons, medulla, and spinal cord. They may be divided into efferent 

 and afferent systems. 



The efferent fibers have their origin in the cells of Purkinje and 

 the dentate nucleus. Some of these fibers emerge from the cere- 

 bellum in the superior 

 peduncles through 

 which they pass to- 

 ward and beneath the 

 corpora quadrigemina 

 to terminate around 

 the cells of the red 

 nucleus. As they ap- 

 proach this nucleus 

 some of the fibers 

 cross the median line 

 and decussate with 

 those coming from the 

 opposite side, while 

 others pursue a 

 straight direction, 

 terminating on the 



<;amp <;irlp Thrnntrh FIG. 230. VIEW OF CEREBELLUM' IN SECTION, 

 le> AND OF FOURTH VENTRICLE, WITH THE 



NEIGHBORING PARTS. (From Sappey.) 

 i. Median groove fourth ventricle, ending 

 below in the calamus scriptorius, with the 

 longitudinal eminences formed by the fas- 

 ciculi teretes, one on each side. 2. The same 

 groove, at the place where the white streaks 

 of the auditory nerve emerge from it to 

 cross the floor of the ventricle. 3. Inferior 

 peduncle of the cerebellum, formed by the 

 restiform body. 4. Posterior pyramid ; 

 above this is the calamus scriptorius. 5, 5. 

 Superior peduncle of cerebellum, _pr pro- 

 cessus e cerebello ad testes. 6, 6. 

 the side of the crura cerebri. 7, 7 

 grooves of the crura cerebri. 

 quadrigemina. (After H-irschfeld 

 veille.) 



the intervention of 

 fibers which arise from 

 the red nucleus and 

 ascend to the cerebral 

 cortex, the cortex is 

 thus connected with 

 both sides of the 

 cerebellum, though 

 chiefly with the oppo- 

 site side. -' . 



Efferent fibers also 

 leave the cerebellum by 

 the middle peduncle 



Fillet to 

 Lateral 

 8. Corpora 

 and Le- 



and pass directly to 



the nucleus pontis, around the cells of which their terminals arborize. 

 Efferent fibers also descend the inferior peduncles and constitute the 

 tract known as the Lowenthal and Marchi tract, situated in the 

 antero-lateral region of the spinal cord in its upper part. 



The afferent fibers come from a variety of sources. Those found 

 in the superior peduncles come from the red nucleus; those in the 

 middle peduncles from the nucleus pontis of the opposite side, having 



