

THE MAMMALIAN NERVOUS SYSTEM 85 



fourth ventricle. These are the nuclei emboliformis, globosus, 

 and fastigii. These nuclei are not easily seen in a dissection of 

 a sheep's brain, but may readily be found in either gross or 

 microscopic sections of the human brain. 



See Cunningham ('15), Figs. 511, 512, and 535; Morris (14), 

 Figs. 637 and 638; Piersol ('13), Figs. 950 and 951; Quain ('09), 

 Vol. Ill, Part 1, Figs. 185-189; Rauber-Kopsch ('12), Fig. 105; 

 Sobotta ('11), Figs. 657 and 658; Spalteholz ('09), Fig. 743; 

 Toldt ('04), Figs. 1182-1189. 



99. Microscopic structure of the cerebellar cortex. Examine 

 and draw the sections of cerebellar cortex provided, and with 

 the aid of your reference books build up a mental picture of the 

 connections of the different types of cortical neurons. See 

 Herrick ('18), Fig. 89 and the accompanying discussion, and 

 references cited at the end of Section 100. 



100. Structure, subdivision, and functions of the cerebellum. 

 Compare the external form of the cerebellum in the fish, 

 sheep, and man, and note that variations in the size of the cere- 

 bellar hemispheres are correlated with those of the pons. 

 What are the fiber connections of the pons, and with what re- 

 mote part of the brain is it in functional connection? Identify 

 the vermis, hemispheres, and flocculus of the cerebellum. 

 Arbor vitce is a name given to the appearance of the cerebellar 

 gray and white matter as seen in median section of the vermis. 

 It is separated into two principal subdivisions by the sulcus 

 primarius (Fig. 10). 



The cerebellum is a great proprioceptive center of coordina- 

 tion. We have already learned that it is connected by afferent 

 fiber tracts with the primary basal proprioceptive apparatus of 

 the spinal cord and brain stem. And it is also intimately re- 

 lated with the cerebral cortex through the cortico-pontile fiber 

 tracts (Section 96, c). Nervous mechanisms for the perform- 

 ance of all simple reflex and voluntary acts are provided in 

 other parts of the central nervous system ; but the participation 

 of the cerebellum is necessary for the performance of all com- 

 plex movements, especially for equilibration, motor coordina- 

 tion, and the maintenance of muscular tone. 



The human cerebellum is subdivided anatomically into a 

 very large number of parts, the names of which are given in all 



