Welcome to 2 minute neuroscience, where I explain neuroscience topics in 2 minutes or
In this installment I will discuss the blood supply of the brain.
The internal carotid arteries supply the brain with about 80% of its blood, while the vertebral
arteries contribute the remaining 20%.
After ascending to the brain, the internal carotid arteries split into the anterior and
middle cerebral arteries.
The anterior cerebral arteries supply the medial frontal and parietal lobes, and they
are connected by the anterior communicating artery.
The middle cerebral arteries supply most of the lateral surface of the cerebral hemispheres.
Before splitting into the middle and anterior cerebral arteries, the internal carotids give
rise to the anterior choroidal arteries, which supply a number of different structures, and
the posterior communicating arteries, which connect the internal carotid arteries to the
posterior cerebral arteries.
The vertebral arteries give rise to the posterior inferior cerebellar arteries, which supply
the inferior surface of the cerebellum and in most brains will also give rise to the
posterior spinal arteries, which supply the posterior spinal cord.
The anterior spinal artery, which supplies the anterior spinal cord, also branches off
the vertebral arteries, then the two vertebral arteries come together to form the basilar
The basilar artery gives rise to the anterior inferior and superior cerebellar arteries,
which supply the rest of the cerebellar surface.
Then, at the the level of the midbrain, the basilar artery splits into two posterior cerebral
The posterior cerebral arteries supply the medial and inferior surfaces of the occipital
and temporal lobes.
The anterior cerebral, internal carotid, and posterior cerebral arteries of both sides
of the brain are all connected, forming what is known as the Circle of Willis.
This interconnection can allow blood flow to continue if a major vessel is blocked on
one side of the brain.