Brain Atlas

Cerebral vasculature 

About 18% of the total blood volume in the body circulates in the brain, accounting for about 2% of the body weight.

The brain receives blood from two pairs of large vessels: the internal carotid arteries , which arise from arteries in the neck, and the vertebral arteries, which arise from arteries in the chest. The vertebral arterial system supplies the brainstem , the cerebellum , the occipital  lobe of the cerebrum , and parts of the thalamus , while the carotid arteries supply the rest of the forebrain . The cerebral vasculature transports oxygen, nutrients and other important substances to the brain to ensure its proper functioning.

The brain uses about 20% of the oxygen absorbed by the lungs. Maintaining a constant blood supply to the brain is essential for normal brain function. Brain tissue deprived of oxygen for less than 1 minute can result in loss of consciousness, and after approximately 5 minutes of blood deprivation, brain tissue is at risk of becoming permanently damaged.