ANGIOLOGY 





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

 callosum, the septum pellucidum, and the head of the caudate nucleus. The 

 inferior 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 gyrus. The anterior branches supply a part of the superior frontal gyrus, 

 and send twigs over the edge of the hemisphere to the superior and middle frontal 

 gyri and upper part of the anterior central gyrus. The middle branches supply 

 the corpus callosum, the cingulate gyrus, the medial surface of the superior frontal 

 gyrus, and the upper part of the anterior central gyrus. The posterior branches 

 supply the precuneus and adjacent lateral surface of the hemisphere. 





FIG. 516. The arteries of the base of the brain. The tempora pole of the cerebrum and a portion of the cerebellar 

 hemisphere have been removed on the right side. 



The Anterior Communicating Artery (a. communicant anterior] connects the two 

 anterior cerebral arteries across the commencement of the longitudinal fissure. 

 Sometimes this vessel is wanting, the two arteries joining together to form a 

 single trunk, which afterward divides ; or it may be wholly, or partially, divided 

 into two. Its length averages about 4 mm., but varies greatly. It gives off some 

 of the antero-medial ganglionic vessels, but these are principally derived from the 

 anterior cerebral. 



9. The middle cerebral artery (a. cerebri media) (Figs. 516, '517), the largest 

 branch of the internal carotid, runs at first lateralward in the lateral cerebral or 

 Sylvian fissure and then backward and upward on the surface of the insula, where 



