580 



Tin: Ai;n:i;ir< 



constitutes tbo jixt,'i-ii>r communicating m-/<r// 

 form tin- middle and anterior a-rclirnl arteries. 



uthor soon bifurcul 



AIITEUIES OF TIIK URAIN. 



B, Medulla oblongata ; p, Pens Varolii ; L, Mastoid lobule; O, Olfactory lobule; 

 C, Chiasma of the optic nerves ; M, Mamillary, or pisiform tubercle; n, Pituitary 

 gland; three-fourths have been excised. 1, 1, Cerebro-spinal arteries: _', Median 

 spinal artery ; 3, Lozenge-shaped anastomosis of the two Mnbro-vpinal arteries, 

 from which result, in front: 4, The basilar trunk (usually the ccrebro-spiual 

 arteries arrive in the middle of the lozenge); 5, 5, Posterior cerebellar arteries ; 

 6, Anterior ditto; 7, Internal carotid artery, with the two curves it makes in 

 the cavernous sinus ; 8, Internal carotid on the sides of tint pituitary gland; 9, 

 Transverse reticulated anastomosis thrown between the two internal carotids 

 behind the pituitary gland; 10, Hifurcatinn of the internal carotid; 11, 11, 

 Posterior cerebral arteries anastomosiug l-hiii'l the pisiform tubercle, receiving 

 in the middle of this anastomosis the two terminal branches of the basilar trunk ; 

 12, Middle cerebral artery; 13, Anterior cerebral artery; 14, Posterior com- 

 municating artery. 



