Cerebrum. 



105 



445. Horizontal Section of the Cerebrum, 



with a view of the Tela choroidea superior. 2 / 3 natural size. 



Between the two posterior pillars of the for nix, Crura 

 posteriora fornicis, is a triangular portion, which is covered by the under 

 surface of the Corpus callosum ; this part of the Corpus cattosum is marked 

 by transverse, longitudinal and oblique lines and is called Lyra Davidis 

 or Psalterium. The posterior pillars of the fornix are continued on into 

 the fimbria. 



The Tela choroidea superior or Velum interpositum is a prolongation 

 of the pia mater ; it is a vascular membrane and can be exposed to 

 view after dividing the fornix and turning aside its two halves ; it has 

 small branches of the Art. profunda cerebri, and in its center two venous 

 trunks, which flow backwards to the single Vena cerebri magna. In it are 

 further found two vascular fringes, the choroid plexuses, Plexus choroidci, 

 which at first lie together (Plexus choroideus medius), and then pass through 

 the foramen of Monro into the lateral ventricles, Plexus choroidei laterales. 



