L>.tS 



DISSECTION OF THE DOG 



Each of these is joined by the posterior communicating branch of the internal 

 carotid artery, and then disappears from the present dissection by passing 

 between the cerebral hemisphere and the cerebral peduncle. The posterior 

 cerebral arteries are chiefly concerned in supplying the posterior part of the 

 cerebral hemispheres. 



Arteria carotis interna. — The termination of the internal carotid 

 artery will be found immediately lateral to the optic chiasma. About this 



Jlulbus olfactorius 



Tractus olfactorius ._ 



Stria lateralis - - 



Trigonum olfactorium-- 



n. opticus- - 



Lobus piriformis .. 



Tuber cinereum _ 

 Corpus luamillare 



- a. cerebri anterior 



a. cerebri media 



, a. chorioidea 



a. communicans posterior 



n. oculo-motortus - 

 n. trochlearis - 

 n. trigeminus 



Pons ' 



n. abducens %z^* 



n. facialis __-■ 

 n. acusticus . - - 

 Cerebellum - ' ' 

 n. glosso-pharyngcus ~ " 

 n. vagus *' 

 n. hypoglossus .-' 

 Medulla oblongata - ' ' 



Fig. 64. — Arteries at the base of the brain 



a. cerebri posterior 



a. ccrebelli anterior 

 ^■*^- a. basilaris 



- a. audiliva interna 

 a. cercbelli posterior 



-, n. accessorius 



point the artery contributes a posterior communicating branch (a. communicans 

 posterior) to the posterior cerebral artery, and then immediately ends by 

 dividing into the middle and anterior cerebral arteries. 



The middle cerebral artery (a. cerebri media) gains the Sylvian fissure, and 

 spreads out over almost the whole of the lateral surface of the cerebral hemi- 

 sphere. A small choroidal artery (a. chorioidea) leaves the middle cerebral close 

 to its commencement, and follows the optic tract to end in the choroid plexus 

 of the lateral ventricle. 



The anterior cerebral artery (a. cerebri anterior) passes dorsal to the optic 

 nerve, and converging upon the median plane, either fuses with its fellow artery 

 of the other side of the brain, or is joined to this by a transverse anterior com- 

 municating artery (a. communicans anterior). The anterior cerebral artery 

 ramifies over the medial surface of the hemisphere. 



