III. Rhombencephalon 



EMBRYOLOGIC DIVISIONS OF THE BRAIN. 33 



( Isthmus Rhombencephali 

 . Metencephalon J Cerebellum, Pons 

 (Hind-brain) Upper half of Fourth Ven- 



tricle 



(Post, vesicle) 



Myelencephalon f Medulla Oblongata 



(After-brain) Lower half of Fourth Ven ' 



I tricle 



The cerebrum embraces the fore-brain and the mid-brain, as 

 shown by the table. So we may make a more comprehensive 

 division of the brain into only two grand divisions: The great 

 brain or cerebrum and the rhombencephalon (Fig. 15). We may 

 now simplify the above table as follows : 



I. Cerebrum, embracing 



End-brain, or Cerebral Hemispheres, etc. 



Inter-brain 



Mid-brain. 



II. Rhombencephalon, comprising 

 Isthmus 



Cerebellum 



Pons 



Medulla Oblongata. 



