BASE. 



r33 



descencTinoj cornea of the lateral ventricle, where it corresponds to the 

 lower part of the eniineutia collateralis. 



Base of the Cerebruji (fig. 375). — From the front of the pons 

 Varolii, two white masses extend, marked on the surface with longi- 

 tudinal strife, and having somewhat the appearance of large bundles of 

 fibres. They pass forwards and outwards to enter the inner and under 

 part of the right and left cerebral hemispheres, of which they are the 

 peduncles or crura. Immediately before entering the corresponding 

 hemisphere, each is crossed by a flattened white cord, named the optic 

 tract (fig. 376), which, adhering by its upper border to the peduncle, 

 is directed forwards and inwards, and meets in front with its fellow of 



Fig. 375. 



Fig. 375.— Base of the Bkain with the Oiugixs of the Cekebkal Nerves. 

 (Alleu Thomson. ) i 



This figure is taken from an adult male brain which had been hardened in alcohol. 



1, superior longitudinal fissure ; 2, within it the straight olfactory tract and sulcus for 

 the convolution; 2', orbital convolutions; 2", inferior frontal convolution; .3, 3, 3, 

 fissure of Sylvius ; 4, 4, 4, temporo-sphenoidal lobe ; 5, 5', occipital lobe ; 6, on the 

 right anterior pyi-amid of the medulla oblongata above the decussation ; 7, amygdaloid 

 lobe of the cerebellum; 8, biventral lobe; '9, lobulus gracilis; 10, posterior inferior 

 lobe ; + , the inferior vermiform process ; I, olfactory bulb ; I', the tract divided on 

 the left side ; II, in the anterior perforated spot, marks the right optic nerve ; the left 

 has been cut short ; III, on the right crus cerebri, denotes the third pair ; IV, the fourth 

 pair ; V, the trigeminus ; VI, on the pons Varolii, the sixth ; VII, also on the pons 

 Varolii, the facial with the auditory nerve on its outer side ; VIII, on the right lobe of 

 the cerebellum below the horizontal fissure and the flocculus, indicates the group of 

 nerves below the auditory, i. c, the glosso-pharyngeal, pneumogastric, and spinal 

 accessory ; IX, on the upper part of the left amygdaloid lobe, denotes the hypo- 

 glossal nerve ; X, on the same, the suboccipital nerve. 



