The 50 premamillary arteries (PremA), arising from 39 posterior communicating arteries (PCoA), were examined in injected human brains. The PremA, which commonly was single (71.8%) and less frequently double (28.2%), more often arose from the PCoA (97.4% ) than from the posterior cerebralartery (PCA) (2.6%). The PremA ranged between 280 and 780 microm in diameter. It gave off side branches to the hypothalamus (23.1%), optic tract (10.2%), mamillary body (17.9%) and the crus cerebri (35.9%). The anastomoses involving the extracerebral segment of the PremA were present in 35.9% of the cases. They varied in caliber from 50 to 230 microm. The intracerebral segment of the PremA ranged from 280 to 490 microm in diameter. Our study gives a precise anatomic basis for safer operations on the aneurysms of the posterior communicating artery and adjacent vessels.
Copyright 2001 Harcourt Publishers Ltd.