Dr. Foville on the Anatomy of the Brain. 21 



which connected at its origin with the base of the convolution 

 of the olfactory nerve, ascends in front of the corpus callo- 

 sum, to the side of which it is applied, winds round its an- 

 terior extremity, then follows its superior aspect, and descend- 

 ing behind its posterior border into the convolution which 

 bounds the fissure of Bichat, returns to the tuberosity si- 

 tuated on the external edge of the quadrangle so often men- 

 tioned. 



This fibrous band therefore, with the quadrangle in which 

 it ceases at its two opposite extremities, describes a large cir- 

 cle in which the corpus callosum is inscribed. The circumfe- 

 rence of this fibrous band forms the base of a convolution 

 whose remarkable disposition has engaged the attention of 

 anatomists. It forms with the latter, on the edge of the corpus 

 callosum contiguous to the hemispheres and the fissure of 

 Bichat, a sort of listing, or border, in which the gray substance 

 of the convolutions ends. I have thought it proper in an ex- 

 tensive work on the anatomy of the brain to name this band 

 cerebral border, and the corresponding convolution, convolu- 

 tion of the border. 



Thus, without multiplying details, we find reaching all 

 along the circumference, or if the term which I have proposed 

 be approved of, along the contracted border forming the li- 

 mit of the extensive gray membrane folded into convolutions 

 on the surface of the brain, a fibrous cord, which forms along 

 with the superficial quadrangle whence it is derived, a com- 

 plete circle round the corpus callosum, and this quadrangle 

 and its immediate dependence communicate on the other side 

 with the sensorial nerves of the brain. 



Let us now take a rapid view of the fibrous parts of the 

 hemispheres. They originate externally in a fasciculated fi- 

 brous layer interposed between the gray masses of the corpus 

 striatum and optic thalamus, and go to the internal surface of 

 the cerebral convolutions, whilst the fibrous layer whence 

 they issue is continued into the inferior part of the crus ce- 

 rebri, and consequently into the anterior pyramids. On the 

 outside of the corpus striatum and optic thalamus, these fi- 

 brous planes of the hemisphere separate into two strata, upon 

 which the cerebral convolutions are raised; and each of these 

 strata or secondary planes becomes united to the external 

 margin of the circular band forming the border of the hemi- 

 spheres. One of these unions takes place in the hollow of 

 the fissure of Sylvius ; the other in all the rest of the internal 

 circumference or border of the gray substance of the convo- 

 lutions. 



Of these two orders of fibres thus differently disposed, the 



