Right and left vertebral arteries join to form which artery?

• A. Basilar artery
• B. Circle of Willis
• C. Internal Carotid Arteries
• D. Posterior Cerebral Arteries

Answer: (A)

Two vertebral arteries merge at the base of the brain to form the basilar artery. This basilar vessel runs along the brainstem and then divides to create the posterior cerebral arteries, which supply the back of the cerebrum. The Circle of Willis, while it connects anterior and posterior circulation, is a ring formed by the internal carotid arteries and the basilar artery with their communicating branches—not something the vertebral arteries do by themselves. The internal carotid arteries handle the anterior circulation, and the posterior cerebral arteries are branches that come off the basilar artery.