BRANCHES OF THE INTERNAL CAROTID. 



511 



upper part of the ascending frontal convolution. The posterior internal frontal 

 branches supply the lobus quadratus and adjacent outer surface of the hemisphere. 



The anterior communicating artery is a short branch, about two lines in 

 length, but of moderate size, connecting together the two anterior cerebral 

 arteries across the longitudinal fissure. Sometimes this vessel is wanting, the 

 two arteries joining together to form a single trunk, which afterward divides. Or 

 the vessel may be wholly or partially divided into two ; frequently it is longer and 

 smaller than usual. It gives off some of the antero-median ganglionic group of 

 vessels, which are, however, principally derived from the anterior cerebral. 



The middle cerebral artery (Fig. 295), the largest branch of the internal carotid, 

 passes obliquely outward along the fissure of Sylvius, and opposite the island of 

 Reil divides into its terminal branches. The branches of the middle cerebral 

 artery are 



Ascending frontal. 

 Ascending parietal. 



Antero-lateral ganglionic. 

 Inferior external frontal. 



Parieto-temporal. 



The antero-lateral ganglionic branches are a group of small arteries which 

 arise at the commencement of the middle cerebral artery ; they pierce the anterior 

 perforated space arid supply the greater part of the caudate nucleus, the lenticular 

 nucleus, the internal capsule, and a part of the optic thalamus. One artery of this 

 group is of larger size than the rest, and is of special importance, as being the 

 artery in the brain most frequently ruptured ; it has been termed by Charcot the 

 "artery of cerebral hemorrhage." It passes up between the lenticular nucleus 

 and the external capsule, and ultimately ends in the caudate nucleus. The 

 inferior external frontal supplies the third or inferior frontal convolution (Broca's 

 convolution) and the outer part of the orbital surface of the frontal lobe. The 

 ascending frontal supplies the ascending frontal convolution. The ascending 

 parietal supplies the ascending parietal convolution and the lower part of the 

 superior parietal convolution. The parieto-temporal supplies the supra-marginal, 

 the superior, and part of the middle temporal convolutions, and the angular gyrus. 



The posterior communicating artery arises from the back part of the internal 

 carotid, runs directly backward, and anastomoses with the posterior cerebral, a 



FISSURE OF 

 ROLANDO. 



Perforating 

 Branches. 



Middle Cerebral 

 Artery. 



FIG. 295. The distribution of the middle cerebral artery. (After Charcot.) 



branch of the basilar. This artery varies considerably in size, being sometimes 

 small, and occasionally so large that the posterior cerebral may be considered as 

 arising from the internal carotid rather than from the basilar. It is frequently 



