Blood supply and venous drainage of the brain
Supply
The blood supply to the brain initially comes from the internal carotid arteries, a branch of the common carotid arteries. the ICAs branch into the anterior and middle carotid arteries. The posterior carotid arteries branch from the basilar artery which is a merge of the vertebral arteries. Often there are communicating arteries between these, the anterior communicating artery connecting the anterior cerebral arteries and the posterior communicating artery connecting the internal carotid arteries to the posterior cerebral arteries. This structure which forms the connections between ACA, MCA, and PCA is called the circle of henle.
The anterior cerebral artery is supplies the anterior 2/3rds of the medial are of the cerebrum. The Middle carotid artery supplies the lateral 4/5ths of the cerebrum and the posterior cerebral artery supplies the medial and lateral rear brain (think occipital lobe inferior temporal lobe and superior brainstem.)
the middle meningeal artery is a branch of the external carotid artery and supplies a good portion of the cranial bones and dura mater. it is vulnerable to bleeds.
The inferior brainstem and cerebellum are supplies by the basilar artery and vertebral arteries, with notable offshoots being the superior cerebellar artery, anterior inferior cerebellar arteries (AICA) and the posterior inferior cerebellar arteries (pica)
Drainage
The venous blood of the brain flows into the sinuses of the meninges. and all ultimately flows into the internal carotids.
the superior sinus is where CSF flowing over the lateral brain ends up and the straight sinus is where the medial csf ends up.
The superior sinus and the straight sinus meet at the confluence of sinuses where the transverse sinuses channel it to the sigmoid sinus and to the IJV
The inferior structures drain into the cavernous sinuses where they can flow into the inferior petrosal sinus which flows into the IJV directly or the superior petrosal sinus which flows into the transverse sinus to the sigmoid sinus and IJV.