BLOOD-VESSELS OF THE CEREBRUM. 



689 





adventitia of the arteries. In the adventitia of the veins there is no pigment, but generally 

 some fat. The grey matter is much more vascular than the white, and when injected, a 

 section of a convolution presents the appearance shown in fig. 478. The nutritive arteries 

 consist of (a) the long medullary arteries (1) which pass from the pia mater through the grey 

 matter into the central white matter or centrum ovale. They are terminal arteries, and do not 

 communicate with each other in their course; thus, they supply independent vascular areas ; 

 nor do they anastomose with any of the arteries derived from the ganglionic system of blood- 

 vessels ; 12,to 15 of them are seen in a section of a convolution, (b) The short cortical nutritive 

 arteries (2) are smaller and shorter than the foregoing. Although some of them enter the 

 white matter, they chiefly supply the cortex, where they form an open meshed plexus in the first 

 layer (a), while in the next layer (6) the plexus of capillaries is dense, the plexus again being 

 wider in the inner layers (c). ] 



[Central or Ganglionic Arteries. From the trunks constituting the circle of Willis (fig. in 

 381), branches are given off, which pass upwards and enter the brain to supply the basal ganglia 

 with blood. They are arranged in 

 several groups, but they are all ter- 



minal, each one supplying its own 

 area, nor do they anastomose with 

 the arteries of the cortex.] 



Cerebral Arteries. From a prac- 

 tical point of view, the distribution 

 of the blood-vessels of the brain is 

 important. The artery of the Syl- 

 vian fissure supplies the motor areas 

 of the brain in animals ; in man, 

 the precentral lobule is supplied by 

 a branch of the anterior cerebral 

 artery (Buret). The region of the 

 third left frontal convolution, which 

 is connected with the -function of 

 speech, is supplied by a special 

 branch of the Sylvian artery. Those 

 areas of the frontal lobes whose in- 

 jury results in disturbance of the 

 intelligence, are supplied by the 

 anterior cerebral artery. Those 

 regions of the cortex cerebri, whose 

 injury, according to Ferrier, causes 

 hemianesthesia, are supplied by the 

 posterior cerebral artery. 



[In connection with the localisa- 

 tion of the centres in the cortex, it 

 is important to be thoroughly ac- 

 quainted with the arrangement of 

 the cerebral convolutions. Each 

 half of the outer cerebral surface is 

 divided by certain fissures into five 

 lobes frontal, parietal, occipital, 

 temporo-sphenoidal, and central, 

 or island of Reil (fig. 481). The 

 frontal lobe (fig. 479) consists of three convolutions, with numerous secondary folds running 

 nearly horizontal, named superior (F x ), middle (F 2 ), and inferior (F 3 ) frontal convolutions. 

 Behind these is a large convolution, the ascending frontal (A), which ascends almost vertically, 

 immediately behind these separated from them, however, by the prsecentral fissure (/ 3 ), and 

 mapped off behind by the fissure of Rolando, or the central sulcus (c).] 



[The parietal lobe (fig. 479, P) is limited in front by the fissure of Rolando, below in part by 

 the Sylvian fissure, and behind by the parieto-occipital fissure. It consists of the ascending 

 parietal (posterior central) convolution (fig. 479, B), which ascends just behind the fissure of 

 Rolando, and parallel to the ascending frontal, with which it is continuous below ; above, it 

 becomes continuous with the superior parietal lobule (Pj), while the latter is separated from the 

 inferior parietal lobule ("pli courbe") by the interparietal sulcus. The inferior parietal lobule 

 consists of (a) a part arching over the upper end of the Sylvian fissure, the supra-marginal 

 convolution (P 2 ), which is continuous with the superior temporo-sphenoidal convolution. 

 Behind is (b) the angular gyrus (P 2 ')> which arches round the posterior end of the parallel 

 fissure, and becomes connected with the middle temporo-sphenoidal convolution.] 



[The temporo-sphenoidal or temporal lobe (fig. 479, T) consists of three horizontal convolu- 



2x 



1. 1, 



Fig. 478. 

 medullary 'arteries ; and 1', 1', in groups between the 



convolutions ; 2, 2, arteries of the cortex cerebri ; a, large 

 meshed plexus in first layer ; b, closer plexus in middle 

 layer ; c, opener plexus in the grey matter next the white 

 substance, with its vessels (d). 



