THE EXTERNAL CONFIGURATION OF THE CEREBRAL HEMISPHERES 



233 



the lateral fissure and the central sulcus play a prominent part. Some of the 

 more important sulci are designated as fissures. This usage is regulated by 

 custom, but it may be said that a number of the fissures are invaginations of 

 the entire thickness of the wall of the hemisphere and produce corresponding 

 elevations projecting into the lateral ventricle. 



The lateral cerebral fissure, or fissure of Sylvius, begins on the basal sur- 

 face of the brain as a deep cleft lateral to the anterior perforated substance 

 (Fig. 172). From this point it extends lateralward between the temporal and 

 frontal lobes to the lateral aspect of the brain, where it divides into three branches 

 (Figs. 166, 167). The anterior horizontal ramus of the lateral fissure runs ros- 



Operculum 



Opercular portion of inferior 

 frontal gyr, 



Superior frontal 

 gyrus 



Middle frontal 

 gyrus 



Frontal pole 

 Triangular portion ** 

 of inf. front, gyrus ..* 



Lateral cerebral fissure^'' 



Temporal pole' 



Superior temporal gyrus-' 

 Superior temporal sulcus'' 



Middle temporal gyrus 



Middle temporal sulcus 

 Inferior temporal gyrus 



Precentral sulcus 



f Anterior central gyrus 

 Central sulcus 



' Posterior central gyrus 

 '' Inter parietal sulcus 



Supramarginal gyrus 

 Interparietal sulcus 

 Angular gyrus 



Superior parietal 

 - lobule 

 '-^-Inferior parietal 



lobule 



-'' Parieto-occipital 

 fissure 



^Lateral occipital 

 gyri 



Occipital pole 

 Transverse occipital sulcus 

 \ Superior temporal sulcus 

 Posterior limb of lateral cerebral fissure 



Fig. 166. Lateral view of the human cerebral hemisphere. (Sobotta-McMurrich.) 



trally and the anterior ascending ramus dorsally into the frontal lobe. The 

 posterior ramus of the lateral fissure is much longer, and runs obliquely toward the 

 occiput and at the same time somewhat dorsally. The terminal part turns 

 dorsally into the parietal lobe. This fissure is, in reality, a deep fossa, at the 

 bottom of which lies the insula. It separates the frontal and parietal lobes 

 which lie dorsal to it from the temporal lobe. 



The central sulcus or fissure of Rolando runs obliquely across the dorsolateral 

 surface of the hemisphere, separating the frontal from the parietal lobe (Figs. 

 166, 167). It begins on the medial surface of the hemisphere a little behind the 

 middle of the dorsal border and extends in a sinuous course rostrally and toward 



