1384 



A MANUAL OF ANATOMY 



from which it is separated by the callosal gyrus. At a point a Uttle 

 behind the centre of the internal surface of the hemisphere it turns 

 upwards and terminates at the supero-mesial border, a short distance 

 behind the upper end of the fissure of Rolando. The calloso- 

 marginal fissure lies between the frontal and limbic lobes, the 

 marginal gyrus being above it and the callosal gyrus below it. 



The collateral fissure is situated on the mferior surface of the 

 hemisphere. It commences near the occipital pole, and extends 

 forwards to near the temporal pole. Posteriorly it has the calcarine 

 fissure above, and in line with, it, and anteriorly it has the hippor 

 campal gyrus on its mesial side. It separates the temporal lobe 

 from the hippocampal portion of the limbic lobe. The middle 



Fig. 580. — The Left Cerebral Hemisphere (Superior Surface). 

 Red = Frontal Lobe. Orange = Parietal Lobe. Blue = Occipital Lobe. 



portion of the collateral fissure gives rise to the eminentia collateralis 

 in the floor of the lateral ventricle. 



The circular or limiting fissure is situated deeply in the anterior 

 part of the posterior horizontal limb of the fissure of Sylvius. It 

 almost surrounds the convolutions which constitute the island of 

 Reil or insula, and is composed of three parts — superior, inferior, 

 and anterior. The superior part separates the insula from the 

 frontal and parietal lobes, the inferior part separates it from the 

 temporal lobe, and the anterior part separates it from the frontal lobe. 

 The circular fissure is deficient in the region of the apex of the insula. 



