THE PERFORATING BRANCHES of the basilar artery were examined in 14 bra
in stems injected with india ink or methylmethacrylate. Three groups o
f the perforators were distinguished: the caudal, the middle, and the
rostral. The caudal perforators varied in number from two to five and
in diameter from 80 to 600 mum. In addition to their terminal branches
, which entered the foramen cecum, the perforators occasionally branch
ed off the pontomedullary artery, the pyramidal vessels, and the hypog
lossal branches. The middle perforators arose either separately from t
he basilar artery or along with the basilar artery collateral branches
. They ranged in number from five to nine and in diameter from 210 to
940 mum. The perforators gave rise to the pontomedullary artery (8.3%)
, the long pontine arteries (25.0%), and the anterolateral vessels (10
0%). The rostral perforators originated from the terminal part of the
basilar artery (91.6%), as well as from the superior cerebellar artery
(91.6%) and the posterolateral artery (16.6%). They varied in number
from one to five and in diameter from 190 to 800 mum. The anastomoses
among various perforating vessels were noted in 41.6 to 66.6% of the c
ases. The authors discussed the possible clinical significance of the
anatomical data observed in this study.