DISSECTING MANUAL. 



and through the optic foramen; posterior communicating, to 

 the posterior cerebral artery; anterior choroidal, entering the 

 choroidal fissure below. [813-817] 



Anterior Cerebral. This curves round the genu of the corpus 

 callosum into the great longitudinal fissure. Branches: ante- 

 rior communicating, to the opposite anterior cerebral ; antero- 

 mesial, entering the base of the brain; internal orbital, to the 

 inner orbital surface; anterior, middle, and posterior internal 

 frontal, to the mesial surface. Middle cerebral : This occupies 

 the fissure of Sylvius. Branches : internal and external striate, 

 entering the base of the brain ; inferior external orbital, to the 

 outer orbital surface; ascending frontal and ascending parietal, 

 ascending on either side of the fissure of Rolando; temporal, 

 running over the upper temporal gyri ; parieto-temporal, run- 

 ning backward. [817] 



Vertebral. This enters at the foramen magnum, ascends 

 inward on the medulla and joins the opposite vertebral at the 

 lower border of the pons, forming the basilar. Branches: 

 meningeal, to the dura; posterior spinal, descending beside 

 the medulla and cord; anterior spinal, joining its fellow and 

 then descending in the antero-median fissure; posterior in- 

 ferior cerebellar, curving round the medulla to enter the 

 vallecula cerebelli. [818] 



Basilar. This occupies the mesial groove of the pons and 

 divides at its upper border into the posterior cerebrals. 

 Branches: transverse, crossing the pons; auditory, accom- 

 panying the auditory nerves; anterior inferior cerebellar, to 

 the lower surfaces of the hemispheres; superior cerebellar, to 

 the upper surfaces. Each posterior cerebral runs backward on 

 the tentorial surface, being joined by the posterior communi- 

 cating branch of the internal carotid. Branches: postero- 

 mesial and postero-lateral, entering the base on the inner and 

 outer sides of the cms; posterior choroidal, to the choroidal 

 fissure above; anterior and posterior temporal, to the occipito- 

 temporal region in front and behind; calcarine, running in the 



[48] 



