492 



THE BRAIN 



distinct band of white matter which is attached by its lateral 

 margin along the concave medial border of the hippocampus. 

 The white matter composing it is continuous with the thin 

 white layer (alveus) which is spread over the surface of the 

 hippocampus, and it presents two free surfaces and a sharp 

 free medial border. The fimbria has been noted already 

 in connection with the hippocampal fissure and the fascia 

 dentata (p. 479), and the relations which it presents to the 

 crus of the fornix and the uncus are pointed out on p. 494. 



Pes hippocampi 

 Hippocampus 

 Anterior collateral eminence 



Uncus 



Frenulum Giacomini 



Fimbria 



Fascia dentata 



Fornix 



H i ppocampal 



gyrus 



Splenium 



Trigonum collaterale 



Calcar avis 



Posterior horn 

 Bulb of cornu 



FIG. 201. Dissection to show the Posterior and Inferior Cornua of the 

 Lateral Ventricle. 



Chorioid Fissure of the Cerebrum. When the pia mater 

 in the region of the hippocampal fissure is removed from the 

 surface of the brain, the chorioid plexus in the interior of the 

 inferior horn of the lateral ventricle is usually withdrawn with 

 it, and a fissure appears between the fimbria and the roof 

 of the ventricular horn. This is termed the chorioid fissure of 

 the cerebrum ; it is the lower part of the great transverse fissure. 

 By the withdrawal of the chorioid plexus it is converted into 

 an artificial gap, which leads directly from the exterior of the 

 brain into the interior of the inferior horn of the lateral 

 ventricle. 



