BLOOD-SUPPLY OF THE BRAIN. 195 



(following the roots of the nerves), and median, the latter passing in the raphe 

 to the grey matter on the posterior surface. The valve of Vieussens and the 

 superior peduncle of the cerebellum receive twigs from the superior cerebellar 

 arteries. The choroid plexuses of the fourth ventricle are supplied by the inferior 

 cerebellar arteries. 



Cerebellum. The under surface is supplied by the inferior cerebellar arteries 

 from the vertebral, and the anterior from the basilar. The upper surface is supplied 

 chiefly by the superior cerebellar arteries from the basilar : its posterior portion 

 from the inferior cerebellar. 



The crura cerebri derive their blood supply from the posterior communicating 

 and the posterior cerebral arteries. Branches of the latter, and also others from the 

 end of the basilar, enter the posterior perforated space. 



The corpora quadrigemina and corpora genie ulata are both supplied by the 

 posterior cerebral artery, but branches of the superior cerebellar arteries pass to the 

 inferior corpora quadrigemina. 



The optic thalamus is supplied above and on the outer, inner and posterior 



Fig. 137. CORTICAL DISTRIBUTION OP THE MIDDLE CEREBRAL ARTEKY. (G. D. T., after Charcot.) 



Diagrammatic. 



CENT., antero-lateral group of central arteries : 1, inferior external frontal artery ; 2, ascending 

 frontal artery ; 3, ascending parietal artery ; 4, parieto-temporal artery. 



sides by branches of the posterior cerebral artery, but its anterior and inner 

 portion receives twigs from the posterior communicating arteries of the circle of 

 Willis and its anterior and outer portion from the middle cerebral. 



Cerebral hemispheres. Frontal lobe. The superior frontal and anterior two- 

 thirds of the middle frontal convolution, with the upper extremity of the ascending 

 frontal, are supplied by the anterior cerebral. The inferior frontal convolution, the 

 posterior extremity of the middle frontal, and the greater part of the ascending 

 frontal convolutions are* supplied by the middle cerebral. The orbital surface is 

 supplied, outside the orbital sulcus, by the middle cerebral : within that sulcus 

 (including the olfactory bulb) by the anterior cerebral. 



Parietal lobe. All the convolutions of the parietal lobe are usually supplied 

 by the middle cerebral artery. 



Occipital lobe. This lobe is supplied entirely by the posterior cerebral artery. 



Temporal lobe. The superior and upper parts of the middle temporal convo- 



o 2 



