Cerebral Convolutions. 



Sulc. 

 extremus 



438. Right Hemisphere, from the inside. After E be r stall er. 



The occipital lobe, Lolus ocdpitalis, is situated at the posterior extremity 

 of the brain; it is bounded in front by the S. ocdpitalis anterior, and below 

 by the S. ocdpitalis later alts; the convolutions separating this lobe from the 

 parietal lobe, have been named Plis de passaye ,mp. and inf. (Fig. 436). 



The temporal or temporo-splicnoidal lobe, Lolus temporalis, is bounded 

 in front and above by the fissure of Sylvius. Three transverse sulci, whose 

 posterior ends are turned upwards (Pars ascendens], divide it into three convolutions. 

 The uppermost of these sulci is always the best developed; it is called the first 

 or superior t e in p o r a 1 (to m p oro-sphenoida 1) or parallel s u 1 c u s, 

 Sulcus temporalis primus s. parallelus; the second or middle temporal 

 sulcus, S. temporalis secundus, is generally interrupted by a vertical gyrus; the 

 third or inferior, S. temporalis tertin.s, lies on the under surface of the lobe. 

 Between them, the first, second and third temporal convolutions, 

 Gyrus temporalis I. s. superior, G-. temporalis II. s. medius, G. temporalis III. s. inferior, 

 lie. Posteriorly, the I. and II. are continuous with the inferior parietal lobule, the 

 III. with the inferior occipital convolution (Fig-. 436 and 437). 



On the internal surface of the hemisphere the Gyrus fornicatus or con- 

 volution of the Corpus c olio sum is seen; it turns around the anterior extre- 

 mity of the Corpus callosum, and is interrupted anteriorly by the Fossa Sylvii; 

 its lower half is the Gyrus hippocampi or uncinate convolution, also called 

 SuLiculum cornu Ammonis, which ends with the uiicus. Above the G. hippocampi 

 is the Fissura hippocampi; concealed in it are the gray Fascia dentata Tarini and 

 the white Fimlria. Superiorly, the Gyrus fornicatus is bounded by the calloso- 

 marginal sulcus, which commences somewhat below the Genu corporis callosi 

 and ends a short distance behind the upper extremity of the sulcus of Rolando. 



Somewhat behind and below the Splenium corporis callosi a deep fissure, 

 which posteriorly divides into two rami, commences in the G. fornicatus; one 

 ramus extends upwards and is called par ieto- occip ital fissure, Fissura 

 parietn-occipitalis s. perpendiculars s interna; the other extending pretty horizontally 

 backwards, is called calcarine fissure, Fissura calcarina, and ends at the 

 pole in the S. extremus. 



