THE CEREBRUM. 



281 



which they are not coterminous. Thus, the frontal lohe 

 extends an inch and a half hehind the coronal suture ; 

 the occipital lobe passes forward for three-fourths inch in 

 front of the lambdoidal suture. The parietal bone covers 

 the parietal lobe or region, and part of the occipital, 

 frontal, and temporo-sphenoidal lobes. The primary 



FIG. 121. LEFT SIDE OF HUMAN BRAIN. 



F, frontal, P, parietal, O, occipital, and T, temporo-sphenoidal lobes ; S, fissure of 

 Sylvius; S', horizontal, S", ascending ramus of S ; c, fissure of Rolando; A. ascending 

 frontal, B, ascending parietal convolutions ; Fl, superior, F2, middle, and F3, inferior, 

 frontal convolutions; PI, superior parietal lobule; P2. inferior parietal lobule; Ol, first, 

 O2, second, and O3, third occipital convolutions ; Tl, first. T2, second, and T3, third 

 temporo-sphenoidal convolutions. 



convolutions are four frontal, first, superior; second, 

 middle; third, inferior; and fourth, ascending; four 

 parietal, first, ascending; second, superior; third, supra- 

 marginal ; and fourth, angular ; three occipital, first, 

 second, and third ; three temporo-sphenoidal, first, 



