Tin: r/.7,-/:/;/;r.v. 



69:5 



Fig. 330. 



\\liich is tho foramen of Monro, or orifice communicating with tho two ven- 

 tricles. On the floor of these cavities is observed two largo eminences, tho 

 corpus strinlinn and the hippocampus ; with a vascular and apparently granu- 

 lated cord forming the cerebral choroid plexus, a dependency of the velum inter- 



"W. 



It now remains to enter into some detail with regard to the anatomical 

 characteristics of all these parts. 



1. The Corpus Callotum. (Figs. 327, 330.) 



The corpus callosum is a kind of arch thrown over the two lateral ven- 

 tricles, \\ hile at the same time it is a commissure uniting the two hemispli 

 It belongs exclusively to mammalia. 



Composed entirely of white substance, it affects a quadrilateral form, 

 being elongated in an antero-posterior direction, and thus presents for study 

 two faces, two borders, and two extremities. 



The superior face, free in the middle, and corresponding to the bottom 

 of the interlobular fissure, is covered right and left by the substance of the 

 hemispheres. It is traversed from before to behind by two white, and 

 generally very delicate, cords, the tractus longitudinalis (the chorda} 

 idlinalu of Lancisii) of the corpus callosum, which lie together on the 

 middle line. The inferior face is 

 divided by the insertion of the sep- 

 tum lucidum into two lateral por- 

 tions, each of which forms the roof 

 of one of the cerebral ventricles. 



The two lateral borders of the 

 corpus callosum disappear in the 

 central substance of the hemis- 

 pheres, where it is almost impos- 

 sible to distinguish their limits. 



The posterior extremity appears 

 at the bottom of the interlobular 

 i , after the destruction of the 

 adhesion usually established above 

 .vcen the two hemispheres, in 

 the form of a thick, rounded en- 

 largement (spleni 11111) folded in 

 l>elow, and confounded with 

 the middle part of tho fornix. It 

 is prolonged, laterally, above the 

 ventricular cavities, by forming two 

 angl- s ( tin- 'i transverse) which aro 

 soon lost in the white central sub- 

 stuiiee of the cerebrum. 



The anterior uln mil if comports 

 : in a similar manner between 

 the anterior lobes of tho hemi- 

 spheres. 



2. Ttie Lateral or Cerebral Ventricles. (Figs. 325, 381.) 



Tho lateral ventricles aro two large elongated cuvitii s t x> a\:ittd in the 

 hemispheres, lying against each other in their anterior moiety, and div. 

 in their posterior part, which is very much curved backwards, outwards, and 

 downwards, to open into tho substance of the nmstoid lobule. 



'I:H S CALLOSUM, AFTKi: KKMoVAL OK 



mi. riTi.i: I-OIHI..N <>i 1111. O.KI.I;I:.\I. 



HKMlSrilKKKS. 



1, Centrum orale of Vieussens; 2, 2, Chordae 

 ! n.'ituiHnales; 4, 4, Cornua, or angles <>f tin- 

 posterior extremity ; 5, 5, Ditto of anterior 

 extremity. 



