174 



TOPOGRAPHICAL ANATOMY OF THE 



the interpeduncular fossa, by dividing into the right and left posterior 

 cerebral arteries. In its course the basilar artery contributes numerous 

 small branches to the medulla (rami meduUares) and pons, and at its 

 termination a multitude of fine branches leave it (and the first part of 

 the posterior cerebral arteries) to enter the posterior perforated sub- 

 stance between the cerebral peduncles. 



Olfactory bulb. - 



II.-- 

 Optic chiasma.-- 



Infundibulum 

 Mammillary body.-]^ 

 Ill 



-A. mcningca anterior. 



-A. cerebri anterior. 



-A. cerebri media. 



,-A. chorioidea. 

 -A. carotis interna. 



- A. communicans posterior, 

 A. cerebri posterior. 



A. cerebelli anterior. 

 Pons. 



— A. auditiva interna. 

 --A. cerebelli posterior. 



Choroid jilexus. 



-A. basilaris. 

 Medulla oblongata. 



1st cervical nerve 



A. cerebrospinalis. 



Fig. 80. — The arteries of the brain. The Roman numerals refer to 

 the cerebral nerves. 



The larger branches of the basilar are the following: — (1) The 

 posterior cerebellar arteries (aa. cerebelli posteriores), right and left, 

 run round the lateral margins of the medulla, to be expended mainly 

 in the posterior part of the cerebellum and the choroid plexuses of the 

 fourth ventricle. (2) The small internal auditory arteries (aa. auditivee 

 internse) are branches either of the basilar or of the posterior cerebellar 

 arteries. Each enters the temporal bone of its own side along with the 

 auditory nerve, and ends in the tympanum. (3) The anterior cerebellar 

 arteries (aa. cerebelli anteriores) are variable in number and point of 



