THE BRAIN. 



27 



Internal Carotid Artery. The internal carotid artery (Fig. 30) enters the 

 petrous portion of the temporal bone, then turns inward and upward through the for- 

 amen lacerum medium, then forward through the cavernous sinus and finally turning 



A. cerebri anterior 



Fissura parieto-occipitalis 



A. cerebri pos- 

 terior 



A. cerebri media 



Fie. 32. Distribution of the A. cerebri anterior, A. cerebri posterior, and A. cerebri media on the lateral 



surface of the brain. 



upward gives off the ophthalmic artery; it then pierces the dura mater just behind 

 the anterior clinoid process, where, after giving off the posterior communicating 

 and anterior choroid, it divides into the anterior and middle cerebral arteries. 



Anterior communicating 

 artery 



Anterior cerebral artery 

 Internal carotid artery 

 Middle cerebral artery 



Anterior choroid artery 



Posterior communicat- 

 ing artery 



Posterior cerebra 

 artery 



Orbital surface of 

 frontal lobe 



Temporal lobe 



Lenticulostriate 

 artery 



FIG. 33. Arteries of the base of the brain, especially the branches of the middle cerebral giving rise to apoplexy. 



Anterior Cerebral Artery. The anterior cerebral (Fig. 31) passes forward and 

 inward over the anterior perforated space, between the olfactory and optic nerves, to 

 the median fissure. It gives off the anterior communicating artery at this point, which 

 joins the anterior cerebral of the opposite side. The main trunk then runs upward 



