THE CEREBRUM. 



797 



The grey substance forming the corpora striata has, for its essential elements, 

 cells analogous to the medium cells of the cerebral cortex. 



Vessels. — The arteries of the brain come from the thrwi cerebral arteries (see 

 the internal carotid). The branches of these vessels form two systems which 

 have a common origin, but which remain distinct at the periphery. The cortical 



Fig. 442. 



BRAIN OF THE OX (UPPER FACE). THREE- FOURTHS NATURAL SIZE. 



B, Neck of the medulla oblongata ; Pj, posterior pyramid of the medulla oblongata ; S, inter-hemi- 

 spherical fissure. 1, Middle lobe of the cerebellum; 2, 2, lateral lobes of the cerebellum; 4,4, 

 anterior part of the fissure of Rolando interrupted by an annectent gvrus uniting convolutions 9 

 and 6 ; 4', inferior part of ditto ; 4", posterior branch ot ditto ; 5, second parietal convolution with its 

 plaits , 6, first parietal convolution with its plaits ; 7, 7, crucial fissure (the sigmoid gyrus surround- 

 ing it is hidden beneath the before-mentioned plait) ; 8, first frontal convolution; 9, union of the 

 second frontal with the limited frontal convolution; 10, limiting front convolution ; 11, lobule of 

 the curved plait. 



system furnishes blood to the pia mater and the grey cortex. The central system 

 leaves the circle of Willis, and is distributed to the ganglionic centres. The 

 arterioles of this system form groups which are generally independent of 

 each other (Duret). 



The venous blood from the centre of the hemispheres issues by the vena 

 53 



