Cerebral Convolutions. 



capital ' 



437. Cerebrum, from above. After Eberstaller. 



The anterior central or ascending frontal convolution is limited 

 in front by the transverse frontal fissure or Sulcns praecentralis, which 

 is usually divided into two parts, the S. praecentralis superior and inferior. The 

 portion of the frontal surface anterior to this convolution is occupied by three 

 gyri, the superior, middle and inferior frontal convolutions, or G-yrl 

 frontalis I, II and III; the fissures separating them are the superior and i n f e r i o r 

 frontal, S. frontalis superior and inferior. The middle frontal convolution is the 

 broadest; it is divided anteriorly by the S. frontalis medius into two portions. 

 At the Gyrus frontalis inferior a Pars ascendens s. opercularis , a Pars triangular is 

 and a Pars orbitalis are distinguished. 



The posterior central or ascending parietal convolution is 

 limited posteriorly by the in tra-parietal fissure or S. retrocentralis ; from 

 it, two convolutions, the superior and inferior parietal lobules, Lobulus 

 parietalis superior and inferior, run backwards; the sulcus separating them is the 

 S. interparietalis. The fissures of the temporal lobe divide the inferior parietal lobule 

 into three portions : G-. supramarginalis, G. angularis and 6r. parietalis posterior. 



About midway between the posterior extremity of the brain and the fissure 

 of Rolando is the deep parieto-occipital fissure, Fissura parieto-occipitalis ; 

 it is only seen to a slight extent on the outer surface, the greater part of it 

 being on the internal surface of the hemisphere ; a little behind it, the S. inter- 

 parietalis ends with a transverse portion : S. occipitalis anterior s. perpendicularis 

 externus. That portion of the external surface, which is bounded in front by the 

 sulcus of Rolando and behind by the parieto-occipital fissure and the S. occipi- 

 talis anterior, is called parietal lobe, Lobus parietalis ; it comprises the ascending 

 parietal convolution, the superior and the inferior parietal lobules. 



