NERVOUS SYSTEM 59 



emerge from the surface of the brain on the outer 

 sides of the crura cerebri. 



B. — Cerebellum. 



1. The Cerebellum is the large unpaired portion 

 of the brain lying just posterior to the cerebral 

 hemispheres. The dorsal surface is marked by nu- 

 merous parallel grooves. It consists of two lateral 

 lobes or hemispheres, and a median portion or 

 vermis. It is connected vi^ith the rest of the brain 

 by three pairs of fibrous bands or crura. The first 

 pair are the superior peduncles. They connect the 

 cerebellum w^ith the corpora quadrigemina. The 

 second and largest pair form the lateral continua- 

 tions of , the pons Varolii. They are known as 

 the middle peduncles. The third pair, the inferior 

 peduncles, connect the cerebellum with the me- 

 dulla oblongata. (Plate VII., a and c.) 



2. The Pons Varolii is the broad, transverse band 

 of fibres on the ventral side of the brain, con- 

 necting the two sides of the cerebellum. (Plate 



VII., A.) 



3. The fifth pair of cranial nerves, the Trigeminal, 

 arise by two roots on either side of the pons Va- 

 rolii. (Plate VII., A.) 



4. The sixth pair of cranial nerves, the Abducens, 

 leave the surface of the brain at the posterior 

 margin of the pons near the mid-ventral line. 

 (Plate VII., A.) 



5. The Anterior Pyramids are the two longitudinal 



