I in: ORGANS OF mi: . 



145 



the foram. n nt' Mn\K<> to the tip of the temporal lobe and leads from 

 the outside into the lateral ventricle. This is the lateral cerebral fit- 

 sure, or t he great Jissw h arcs (fissura cerebri transv. 



In a preparation made in the manner described the hippocampal 

 is to be seen at a sh< ro from the choroid plexus and 



parallel to it (figs. 253 an.l t nd fig. 254 /*). This increases 



in .-i/.e toward the apex of tin- interim- cornu. and in the completely 

 formed brain produces the cornu Ammonis or pes hippocampi. 

 Consequently that part of the lateral vent rifle en<-lo>. d in the tem- 

 poral lobe becomes (as the result ,!' r.vo inMdings of its m. 

 wall) restricted 



by two pro- ^^ * A* 



jections, the 

 choroid plexus 

 and the cornu 

 Ammonis. As 

 in the between 

 hrain and me- 

 dulla oblon- 



^;ila. tl.- 

 thelial covering 

 of the choroid 

 plexus is con- 

 tinuous with 

 the thicker 

 ner ve-s u 1- 

 oe of the 

 cornu A m- 

 The 



transition i> etYec-ted ly means of a thin medullary plate, which in 

 anatomy is described as the tinihrin. 



Inasmuch as the occipital lobe with its cavity develops as an 

 evagination of the ring-lobe, the fissura calcarina belonging to it 

 i> therefore developed somewhat later than the arcuate fissure 

 (fig. 241 fc). It appears at the end of the third month as a fissure 

 1. ranching off from the latter, and rui.s in a hori/.ontal direction until 

 near the apex of the occipital lobe. It invaginates the median wall 

 of the lobe and produces th- IWt, which invades the posterior 



cornu in the same way as the hippocampus major (cornu Amnx 

 does the inferior cornu. At the beginning of the fourth month the 

 fissura occipitalis (fig. 241 fo) is added to it. The latter rises from 



Fig. 255.- Transverse section through 



3-8 cm. in length, nftor M:n u KOVICB. Magnified 9 diameter*. 

 The section passes through the foramina of M 

 hs, Great falx cerebri which fills up the interpallial fissure ; A 1 , A*, plane 



inner [median] and convex outer wall of the cerebral hemisphere; 



agf, fold : ; >caropal fold ; /, f 



n, lateral M-MM 



di, optic chiasma ; frx", descending root of the foraix. 



