754 DISSECTION OF THE BRAIN. 



convolution running across its floor from the cuneate lobe (C'imjJi 



to the back part of the fifth temporal or uncinate convolution (u)Ji 



The back part of the uncinate convolution is commonly styled the I 



A taut lingual, and the small gyms crossing the calcai 'in e fissure is therefore!! 



convolution, the cuneo-liiiguol annectant convolution. 



Hippocam- The hippocampal or dentate fissure (h) is placed in front of thel 

 pal tissm-e. foregoing, at the inner margin of the lower portion of the heini-l 

 sphere, and separates the uncinate, or hippocampal convolution (u)| 

 from the taenia hippocampi (TH), which will be revealed by gently I 

 P en ^ n g U P tne fissure. The fissure produces the hippocampus I 

 major in the descending cornu of the lateral ventricle, and its! 

 relations will be better seen when that body is examined. 



Collateral The collateral fissure (coll) represents the fourth temporal sulcus I 



fissure. an( j gives r i se to the collateral eminence in the lateral ventricle. I 



It extends from near the posterior extremity of the hemisphere to I 



the fore part of the temporal lobe, and is frequently broken up into I 



two or three parts by cross gyri. 



Third The third temporal sulcus (IT) is usually broken into two or three I 



suicus ial P arts which run more or less parallel with the outer margin of the 

 temporal lobe. The posterior extremity of the sulcus is sometimes 

 prolonged on to the outer surface for a short distance. 



Caiiosai The callosal sulcus is the hollow between the upper surface of the 



sulcus, corpus callosum and the lower surface of the callosal convolution j 



(Oatt). 



Marginal CONVOLUTIONS. The marginal convolution (M) occupies the space 



tion. between the calloso-margiiial sulcus and the border of the hemi- 



sphere. It is much subdivided, and at its posterior extremity a 

 small portion is marked off by a short vertical furrow, and is 

 Oval lobule, distinguished as the oval or paracentral lobule (Ov.) The marginal 

 convolution is continuous over the border of the hemisphere with 

 the internal orbital and superior frontal convolutions, while the 

 oval lobule is formed by the upper end of the ascending frontal 

 and parietal convolutions. 



Convoiu- The callosal convolution (gyrus fornicatus ; Call] is narrower and 



corpus ' simpler than the marginal. Beginning below the rostrum of the 



callosum. corpus callosum, this convolution follows the curve of that body, 



and turns downwards behind its posterior extremity to end in a thin 



part which joins the uncinate convolution (u). It is bounded in 



the greater part of its extent by the calloso-marginal sulcus, but 



behind the spot where this furrow turns upwards it is continuous 



with the prsecuneus, or quadrate lobule (Q). Near its ending, it 



is limited below by the calcarine fissure. Between it and the 



corpus callosum is the callosal sulcus. 



The prcecuneus or quadrate lobule (Q) is placed between the end 



lobule. of the calloso-marginal sulcus and the parieto-occipital fissure. 



Much subdivided by secondary furrows, it reaches the margin of 



the hemisphere above, where it is continuous with the superior 



parietal lobule ; it joins the callosal convolution below. 



lobule? 6 1" ne cunea ^ e lobule (occipital lobule ; Gun) is triangular in shape, 



the base being formed by the margin of the hemisphere. In front 



