THE NERVOUS SYSTEM 



1349 



column of the cord sweeps obliquely across to the opposite side, 

 where it forms the greater part of the pyramid of that side. The 

 parts, therefore, of the lateral column of the cord which form the 

 lateral area of the bulb below the olive are (i) the dorsal or direct 

 spino-cerebellar tract, (2) the ventral spino-cerebeUar tract, and 

 (3) the lateral ground-bundle. The dorsal spino-cerebeDar tract as 

 it ascends, soon inclines obliquely backwards to join the restiform 

 body. The ventral spino-cerebellar tract and lateral ground- 

 bundle ascend until they reach the lower end of the olive. They 

 then for the most part sink deeply and ascend to the pons Varolii 

 on the dorsal or deep aspect of the olive. A few of the fibres, 

 however, remain on the surface and ascend in the small interval 



Middle Commissure 

 Pineal Peduncle ; Third Ventricle 



(Habenula) \ : 



^, Optic Thalamus 



Upper Quadrigeminal Body 

 Lower Quadrigeminal Body 

 ■^^^.Crus Cerebri 



~""-- Frenulum Veli 

 ^""-^ Valve of Vieussens 

 ^ ~ --.Superior Peduncle of 

 Cerebellum 

 ■~-Do., do. (cut) 



~~ Striae Acusticae 

 "^ ^^ ^"-,Trigonum Acusticum (base) 

 n>L^ ^"-^Trigonura Hypoglossi 

 •19^^ ^-~ Trigonum Vagi 

 ■/^ ^-^. Tubercle of Rolando 



-Clava 

 — Funiculus Gracilis 



Funictilus Cuneatus 



Median Furrow 



Erainentia Teres 



Sujjerior Fovea, .^_ 



Stris Acusticae — Iv - 



Inferior Fovea 



Cnneate Tubercle— 



Fig. 564. — ^The Floor of the Fourth Ventricle and Adjacent Parts. 



which lies between the outer part of the olive and the funiculi of 

 the glosso-pharyngeal and pneumogastric nerves. 



The lateral area of the bulb below the olive thus represents the 

 dorsal or direct spino-cerebellar tract, ventral spino-cerebellar 

 tract, and lateral ground-bundle of the lateral colrunn of the spinal 

 cord of the same side. 



Superiorly, as stated, the lateral area presents an oval eminence, 

 called the olive. It lies between the funiculi of the hypoglossal 

 nerve on the one hand, and the funiculi of the glosso-pharyngeal 

 and pneumogastric nerves on the other, with the intervention of 

 some ascending fibres belonging to the ventral spino-cerebellar 

 tract. Its long axis is placed vertically, and in this diiection it 



