504 



COMPARATIVE ANATOMY 



arises from the basal wall of the hemisphere. The archistriatum is 

 presumably chiefly olfactory in function, but the neostriatum is a receptory 

 center for fibers from the thalamus. 



These divisions of the striate body persist in mammals in which the 

 archistriatum becomes the amygdaloid nucleus, the paleostriatum is the 



Insula 



Olfactory tract 

 Hypophysis 



Anterior 

 perforated 

 substance 



Mamillary 

 bodies 



Cerebral 

 peduncle 



Semilunar 



(Gasserian) 



ganglion 



Hypoglossal nerve (XH) 



Pyramid 



Decussation of pyramids '' 



Fig. 420. — Ventral view of brain stem. 



1 Optic nerve (11) 



Optic tract 

 / 



Tuber cinereum 



^"*' ^^ Oculomoto'- 



^,.-. nerve (HI) 



Lateral geni- 

 culate body 



~ Trochlear nerve 



■'■^^"--^M.SLstica.toT 

 nerve 



■-■jTrigeminus 



Abducens 

 — (VI) 

 __Brachium of 

 pons 



Facialis (VII) 



~~^_Glossopalatine 



nerve 

 '^N^ Cochlear and 

 ^vestibular nerves 

 (Vni) 

 » Glossopharyngeal 

 nerve (IX) 



'Vagus nerve (X) 



^^N Accessory nerve (XI) 

 (spinal accessory) 



"^v Cervical I 



Cervical II 



(From Morris, after Allen Thomson.) 



globus pallidus, and the neostriatum divides into caudate nucleus and 

 putamen. With the elongation of the hemispheres, the striatum is 

 lengthened and rests upon the thalamus like a sac of meal on a packhorse. 

 The division of the striate body is a result of the growth of fiber tracts 

 such as the internal capsule which conveys ascending and descending 



