264 INTRODUCTION TO NEUROLOGY 



In the embryologic development of the human brain the cere- 

 bral hemispheres grow out as lateral pouches from the anterior 

 end of the neural tube (Figs. 46-54, pp. 116-121). These pouches 

 are hollow and the cavities within them are the lateral ventricles 

 (also called the first and second ventricles), each of which com- 

 municates with the third ventricle of the thalamus by a narrow 

 opening, the interventricular foramen or foramen of Monro. 



In a simply organized brain like that of the frog (Fig. 1 19) the 

 olfactory bulb forms the anterior end of each cerebral hemi- 



Olfactory nerve 



Ifactory bulb 

 Lateral ventricle 

 Corpus striatum 

 Lamina tenn'malis 

 Interventricular foramen 

 Third ventricle 

 .Optic lobe 

 .Cerebellum 



'ourth ventricle 



Fig. 119. Diagrammatic representation of an amphibian brain from 

 which the roof of the thalamus and cerebral hemisphere has been dissected 

 off on the right side, exposing the third and the lateral ventricles and the 

 interventricular foramen (foramen of Monro). The membranous roof of 

 the fourth ventricle has also been removed. 



sphere, behind which the massive wall contains ventrally the 

 basal olfactory centers (p. 218), laterally the corpus striatum 

 (p. 168), and dorsally the cerebral cortex or pallium (which has 



lems Relating to the Evolution of the Brain, The Lancet for January 1, 15, 

 and 22, 1910. 



SMITH, G. ELLIOT. 1912. The Evolution of Man, Report of the Anthro- 

 pological Section of the British Assoc. for the Advancement of Science, 

 Dundee Meeting. Printed also in Nature (London) for Sept. 26, 1912, 

 and in the Smithsonian Report (Washington) for 1912, pp. 553-572. 



