The<unk>  are a number of small vessels which come off at right angles from either side of the basilar artery and supply the pons and adjacent parts of the brain.
Branches of basilar artery - 
The basilar artery extends from the lower to the upper border of the pons. It lies in the median groove under the cover of arachnoid membrane.It divides into following branches on either side-<unk>  artery 
Anterior inferior cerebellar artery (AICA)
Superior Cerebellar artery (SCA)
Posterior cerebral artery 
Internal auditory artery
Perforators - 
The small branches of the basilar artery are also known as perforators and this peroforating<unk>  can be classified into three subgroups : 
(i) rostral (mesencephalic perforating<unk> , distal to the SCA); 
(ii) middle<unk>  perforating<unk> , between the SCA and AICA); 
(iii) caudal (proximal to the AICA).
There are between two and five rostral BA perforators, which have an average diameter of 250 μm; the caudal perforators vary in diameter from 80 to 600 μm. The midbasilar artery gives rise to between five and nine perforators with a diameter ranging from 210 to 940 μm, which originate directly from the BA or from a common trunk linked to the superolateral or inferolateral<unk>  artery. The middle basilar perforator includes the pontomedullary artery, the long<unk>  artery/circumferential artery, and the anterolateral vessels.
The knowledge of this perforators is important to define the type of aneurysm according to the location of the perforating parent artery.
References:
Pontine arteries
Vertebral artery
Internal carotid artery
Basilar artery
Labyrinthine artery
Posterior communicating artery
Middle cerebral artery
Posterior inferior cerebellar artery