Cerebral Convolutions. 



99 



439. Cerebrum, from below. After Eberstaller. 



The cuneate lobule, Cuneus, is a wedge-shaped area lying between 

 the calcarine and parieto-occipital fissures; the quadrate lobule, Prae- 

 cuneus, is a four-sided area lying between the parieto-occipital and cal- 

 loso -marginal fissures; the latter is imperfectly separated from the Gyrus 

 fornicatus by the Sulcus subparietalis. The prolongation of the anterior cen- 

 tral convolution on the median surface of the hemisphere, forms part of 

 the paracentral lobule, Lobulus par acentr alts. From the summit of 

 the cuneus a deep convolution runs through the lower end of the parieto- 

 occipital fissure to the Gyr. fornicatus (Fig. 438). 



On the under surface of the frontal lobe are only two fissures: 

 1. the olfactory fissure, Sulcus olfactorius, in which the olfactory 

 tract and bulb lie, 2. to the side of this is the orbital fissure, Sulcus 

 orbitalis, which varies a great deal. The orbital portion of the 

 superior frontal convolution, Gyr. frontalis superior, is called the 

 Gyr. rectus ; the part between the orbital sulcus and Fossa Sylvii is the orbi- 

 tal portion of the inferior frontal convolution (Fig. 436). 



On the under surface of the united temporal and occipital lobes a deep 

 antero-posterior sulcus, the o ecipito -temp or al sulcus, separates a 

 lateral from a median portion; the former lies between this sulcus and the 

 third or inferior temporal sulcus and is called Gyr. occipito-temporalis lateralis 

 s. fusiformis ; the latter, Gyr. occipito-temporalis medialis, whose anterior 

 portion is called Gyr. hippocampi, the posterior, Lobulus lingualis. 



Heitzmann, Atlas. II. 14 



