288 PRACTICAL ANATOMY. 



It is numerously perforated for the passage of vessels to 

 the. corpus striatum. 



6. Lamina Cinerea. A gray layer continuous with 

 the termination of the corpus callosum. It lies below 

 the chiasm of the optic nerves. 



7. Optic Nerves, Chiasm and Tracts. The second 

 pair of nerves. The tracts begin at the corpora genicu- 

 lata, curve around the outer part of the crura cerebri; 

 cross, forming the chiasm, which sends off the optic 

 nerves. 



8. Tuber Cinereum. The gray, dome-shaped struc- 

 ture that extends between the crura cerebri. It forms 

 the floor of the third ventricle. 



9. Pituitary Body and Infundibulum. The infun- 

 dibulum is a funnel-shaped process of the tuber cinereum. 

 It hangs down and is drawn slightly forward. It pre- 

 sents a central canal. Attached to it is the pituitary 

 body, a trilobed structure situated in the sella turcica. 



10. Corpora Albicantia. Located near the poste- 

 rior part of the tuber cinereum, formed by reduplication 

 of the anterior pillars of the fornix. 



11. Posterior Perforated Space. Behind the corpora 

 albicantia ; transmits vessels to the optic thalami. 



12. Crura Cerebri. Formed by the continuation of 

 the fibres of the medulla. As they emerge from behind 

 the pons the two crura diverge. They are about one 

 inch broad, one and three-fourths inches long, and con- 

 tain a central gray portion, the locus niger. 



13. Third Pair of Nerves. Motor oculi, wind around 

 the under side of the crura. 



14. Fourth Pair of Nerves. Patheticus, emerge 

 from around the outer border of crura. 



15. Pons Varolii. Consists of white and gray mat- 

 ter. The white fibres run both transversely and longi- 





