618 



THE VASCULAR SYSTEMS 



substance and lamina terminalis, and supply the rostrum of the corpus callosum, 

 the septum lucidum, and the head of the caudate nucleus. 



The inferior internal frontal branches, two or three in number, are distributed to 

 the orbital surface of the frontal lobe, where they supply the olfactory lobe, gyrus 

 rectus, and internal orbital (mesorbital) convolution. 



The anterior internal frontal supply a part of the mesal surface of the prefrontal 

 region, and send branches over the edge of the hemisphere to the superfrontal 

 and medifrontal gyre and upper part of the precentral gyre. 



The middle internal frontal supplies the corpus callosum, the callosal gyre, the 

 mesal surface of the superfrontal convolution, and the dorsal part of the pre- 

 central gyre. 



The posterior internal frontal supplies the precuneus and adjacent outer surface 

 of the hemisphere. 



The anterior communicating artery (a. praecommunicans, a. communicans ante- 

 rior} is a short branch, about 4 mm. in length, but of moderate size, connecting 

 the two anterior cerebral arteries across the intercerebral fissure. Sometimes 



ANTERO-LATtm, 

 UliaiONIC OR PER- 

 FORATING BRtNCHCV 

 MIDDLE CEREBRAL ARTER 



FIG. 453. The distribution of the middle cerebral artery. (After Charcot.) 



this vessel is wanting, the two arteries joining 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 (a. medicerebmlis, a. cerebri media) (Fig. 453), 

 the largest branch of the internal carotid, passes obliquely outward along the 

 sylvian fissure, and divides opposite the island of Reil into its terminal branches. 



Branches. The branches of the middle cerebral artery are: 



Antero-lateral ganglionic. 

 Inferior external frontal. 

 Ascending frontal. 



Ascending parietal. 



Parietotemporal. 



Temporal. 



The antero-lateral ganglionic branches, a group of small arteries which arise at 

 the commencement of the middle cerebral artery, are arranged in two sets; one, 

 the internal striate, passes upward through the inner segment of the lenticular 

 nucleus, and supplies it, the caudate nucleus, and the internal capsule; the other. 



