722 DISSECTION OF THE BRAIN. 



posterior third of the cerebrum, as described receives its blood 

 through these branches of the subclavian arteries. 



Internal The INTERNAL CAROTID ARTERY (fig. 257, J ) terminates in branches 



for the remaining part of the cerebrum. The vessel emerges from 

 the cavernous sinus internal to the anterior clinoid process, and 



ends in divides at the inner end of the fissure of Sylvius into cerebral and 



cerebral . 



arteries : communicating arteries. 



branches. BRANCHES. In the skull the carotid gives off the ophthalmic 

 offset, before it ends in the following branches (fig. 257) : 



a. Posterior communicating. 



b. Anterior cerebral. 



c. Middle cerebral. 



d. Anterior choroid. 



Posterior a. The posterior communicating artery ( 6 ) is generally a small 

 eating. vessel, directed backwards on the inner side of the third nerve, 

 to join the posterior cerebral artery near the pons. 



Anterior I. The ANTERIOR CEREBRAL ARTERY (fig. 257, 2 , and fig. 258) Supplies 



artery : the inner part of the cerebral hemisphere. It is directed forwards to 

 the median fissure between the halves of the large brain ; and as it 



its com- is about to enter the fissure, it is united to its fellow by a short thick 

 mg ' branch the anterior communicating (fig. 257, 3 ). Then passing into 

 the fissure, it bends- round the fore part of the corpus callosum, 

 and is continued backwards along the upper surface of that body, 

 sending its branches nearly to the posterior extremity of the 

 hemisphere. 



Its branches, like those of the posterior cerebral, consist of deep or 

 central and superficial or cortical arteries. 



central, The central branches (antero-mesial) consist of two or three small 



offsets which arise near the beginning of the artery, and penetrate 

 the anterior perforated space at the inner end of the fissure of Sylvius 

 to reach the fore part of the corpus striatum in the interior of the 

 hemisphere. 



and cortical The cortical branches supply the fore and upper parts of the 

 internal surface of the hemisphere, extending backwards as far as 

 the parieto-occipital fissure ; and some turn round the margin to 

 the adjacent portions of the frontal lobe on both the upper and 

 lower aspects. 



They are named as follows : (fig. 258). 



1. Internal orbital. 



2. Internal frontal. 



3. Pra3cuneal. 



4. The artery of the corpus callosum. 



Internal 1. The internal orbital is distributed to the inner part of the under, 



orbital. or orbital sur face of the frontal lobe. 



internal 2. The internal frontal are two or three branches given off 



frontal. from the convexity of the vessel as it winds round the anterior end 

 of the corpus callosum, and are distributed to the whole of the 

 mesial surface of the frontal lobe and to a small part of its outer or 

 convex surface (fig. 259). 



