The basilar artery lies at the front of the brainstem in the midline and is formed from the union of the two vertebral arteries.
Diagram of the arterial circulation at the base of the brain (inferior view). The basilar artery terminates by splitting into the left and right posterior cerebral arteries.
The two vertebral arteries and the basilar artery are known as the vertebral basilar system, which supplies blood to the posterior part of the circle of Willis and joins with blood supplied to the anterior part of the circle of Willis from the internal carotid arteries.[4][5][6]
Structure
The diameter of the basilar artery range from 1.5 to 6.6 mm.[7]
The internal carotid and vertebral arteries (Right side view)
Basilar artery
The arteries of the base of the brain. Basilar artery labeled below center. The temporal pole of the cerebrum and the cerebellar hemisphere have been removed on the right side. Inferior aspect (viewed from below).