Which arteries join together to form the basilar artery?

• A. Vertebral arteries
• B. Carotid arteries
• C. Cerebral arteries
• D. Pial arteries

Answer: (A)

The basilar artery is formed by the fusion of the two vertebral arteries. As these arteries ascend through the neck and into the skull, they join at the level of the lower brainstem (base of the pons) to create the basilar artery, which then runs along the ventral surface of the brainstem and gives rise to the posterior circulation.

Other vessels don’t form it: the carotid arteries contribute to the anterior circulation, “cerebral arteries” is a broad term for many vessels, and pial arteries are small surface vessels on the brain’s surface.