THE EXTERNAL CONFIGURATION OF THE CEREBRAL HEMISPHERES 



241 



stands by itself and is sometimes designated as the limbic lobe. This plan of 

 subdivision, which was based on the erroneous belief that all portions of the 

 gyrus fornicatus belonged to the rhinencephalon, should be abandoned. A 

 simpler and more logical arrangement assigns the hippocampal gyrus and uncus 

 to the temporal lobe and divides the gyrus cinguli between the frontal and 

 parietal lobes. 



Longitudinal fissure of cerebrum 

 / Frontal pole 



rectus 

 ^Olfactory sulcus 



Orbital sulci 



Olfactory trigone 

 Mammillary body 

 .-Uncus 



L Middle temporal sulcus 

 Base of cerebral peduncle 

 Substantia nigra 



Optic chiasma 



Orbital gyri 

 Anterior perforated substance^ 



Temporal pole._ 



Lateral cerebral 

 (Sylvian) fissure 



Middle temporal sulcus-.. 



Tuber cinereum- 



I'VE* "*TWk TjiW ""* 3* !^^fc ^^^^B^^^T m j^s t ^H9T 



^Inferior temporal gyrus 



Fusiform gyrus 



Hippocampal gyrus 

 Corpus quadrigeminum 

 Isthmus of gyms fornicatus 

 Lingual gyrus 

 "Gyrus cinguli 



\ Splenium of corpus callosum 

 \ Parieto-occipital fissure 

 Occipital pole 



Fig. 172. Basal aspect of the human cerebral hemisphere. (Sobotta-McMurrich.) 



The basal surface of the hemisphere (Fig. 172) consists of two parts: (1) 

 the ventral surface of the temporal lobe, whose sulci and gyri have been de- 

 scribed in a preceding paragraph, and which rests upon the tentorium cerebelli 

 and the floor of the middle cranial fossa; and (2) the orbital surface of the frontal 

 lobe resting upon the floor of the anterior cranial fossa. The latter surface 

 presents near its medial border the olfactory sulcus, a straight, deep furrow, 

 directed rostrally and somewhat medially, that lodges the olfactory tract and 

 bulb. To its medial side is found the gyrus rectus. The remainder of the 

 orbital surface of the frontal lobe is subdivided by irregular orbital sulci into 

 equally irregular orbital gyri. 



16 



Hippocampal fissure 



Collateral fissure' 

 Inferior temporal sulcus' 



Cerebral aqueduct 



Collateral fissure 



CuneuS 



