I390 



A MANUAL OF ANATOMY 



central sulcus, and below the ramus horizontalis and ramus occi- 

 pitalis. It is broken up into three gyri, namely, supramarginal, 

 angular, and postparietaJ, in this order from before backwards. 

 The supramarginal gyrus arches round the ascending extremity of 

 the posterior limb of the fissure of Sylvius. It is continuous in 

 front with the ascending parietal gyrus below the lower end of the 

 inferior postcentral sulcus ; posteriorly with the angular gyrus ; 

 and postero-inferiorly with the first temporal gyrus. The angular 

 gyrus arches round the ascending extremity of the first temporal 

 or parallel sulcus, and is continuous with the second temporal 

 gyrus. The postparietal gyrus arches round the ascending ex- 

 tremity of the second temporal sulcus, and is continuous with the 

 third temporal gyrus. 

 Internal Surface of the Parietal Lobe.— The internal or mesial 



Fimbria 

 Gyrus Dentatus 



Fig. 585. — The Mesial Surface of the Right Cerebral Hemisphere 



(HiRSCHFELD AND LEVEILL^). 



surface is of quadrilateral outline, and constitutes the quadrate 

 lobule or praecuneus. It is bounded in front by the upturned 

 posterior extremity of the calloso -marginal sulcus, behind by the 

 internal part of the parieto-occipital fissure, and below by the 

 postlimbic sulcus and a portion of the limbic lobe. 



Occipital Lobe. — ^This lobe lies behind the parietal and temporal 

 lobes, and forms the posterior part of the cerebral hemisphere. 



Externally the lobe is bounded in front by the external part of 

 the parieto-occipital fissure, and a line connecting this fissure with 

 the pre-occipital notch on the infero-lateral border of the hemi- 

 sphere. Internally it is bounded in front by the internal part of 

 the parieto-occipital fissure, which separates it from the quadrate 

 lobule, or precuneus, of the parietal lobe. Inferiorlv it is continuous 

 with the temporal and limbic lobes, but the separation may be 

 indicated by a line connecting the pre-occipital notch with the 



