THE NERVOUS SYSTEM 



1381 



TELENCEPHALON. 

 Cerebral Hemispheres. 



The cerebral hemispheres are two in number, right and left. 

 Each is semi-ovoid, and presents two extremities and three surfaces. 



The extremities are anterior and posterior. The anterior ex- 

 tremity is thick and round, and its most projecting part is called 



Great Longitudinal 

 Fissure 



Inferior Frontal 

 Gyrus 



Sulcus Occipitalis^ 

 Lateralis 



Sulcus Occipitalis"' 

 Sulcus Occipitalis Transversus' 



External Parieto-occipital Fissure 



Fig. 579. — The Cerebral Hemispheres (Superior View). 



the frontal pole. The posterior extremity is narrow and pointed, 

 and its most projecting part is called the occipital pole. The 

 surfaces are external, internal, and inferior. The external surface 

 is convex, in adaptation to the concavity of the cranial vault. The 

 internal surface is flat and vertical, and it forms the lateral boundary 

 of the great longitudinal fissure. For the most part it is in contact 

 with the falx cerebri. The inferior surface is irregular, being 

 adapted to the corresponding lateral divisions of the anterior and 

 middle fossae of the interior of the base of the skull and the upper 

 surface of the tentorium cerebelh. It is crossed transversely by a 

 deep cleft, representing the stem of the fissure of Sylvius. The 



