468 



THE BRAIN 



Gyrus Frontalis Inferior. The inferior frontal gyrus 

 possesses a special interest and importance, on account 

 of the supposed localisation within it, on the left side, of the 



Longitudinal fissure 



Olfactory sulcus 



Olfactory bulb. 



Orbital sulcus. J. 



Olfactory tract- 

 Temporal pole- 



Incisura 

 temporalis - 



Inferior 

 -frontal 

 gyrus 



Collatera 

 fissure 



Calcarine fissure 



Longitudinal fissure 



FIG. 1 88. Gyri and Sulci on the Tentorial and Orbital Surfaces of the 

 Cerebral Hemispheres. 



speech-centre. It consists of an upper non-opercular and a 

 lower opercular portion. The latter is cut up into three parts 

 by the two anterior branches of the lateral fissure. These 



