BRAIN 



173 



The brain is enclosed by the cranium, and the lower and 

 hind-part of the brain, called the medulla, is prolonged through 

 the foramen magnum of the occipital bone into the vertebral 

 canal. The upper part of the brain the cerebrum is the 

 larger; it is divided longitudinally by a deep cleft into two 

 halves, each of which are divided again into lobes, correspond- 



Olfactory Bulb 

 Olfactory Tract 



Optic Nerve 



Optic Commissure -mnjpr 



Optic Tract 

 Third Nerve 



Fourth Nerve 



Fifth Nerve 

 Sixth Nerv 

 Facial Nerve 

 Pars Intermedia -' 



Auditory Nerve '" 

 Glosso-pharyngeul Nerve - 

 Pneumogastric Nerve 

 Spinal Accessory Nerve 



Hypoglossal Nerve 



Locus Perforates - 

 Anticus 



- Tuber Cinereum 



Corpus Albicans 

 Crus Cerebri 



Locus Perforatus- 

 Posticus 



Pons Varolii 



Medulla Oblongata 



Spinal Cord 



FIG. 61. BASE OF THE BRAIN. 



ing with, in shape and position, the bones of the cranium 

 namely, frontal, parietal, temporal, and occipital. These are 

 again subdivided by numerous clefts or sulci.' Beneath the 

 occipital lobes of the cerebrum lies the cerebellum, or hind-brain, 

 much smaller than the cerebrum. It also is divided longitu- 

 dinally into two principal lobes, which are again subdivided by 



