Which artery supplies 30% of brain blood flow?

• A. External Carotid Artery
• B. Internal Carotid Artery
• C. Vertebral Artery
• D. Basilar Artery

Answer: (A)

The brain’s blood supply comes from two main streams: the anterior circulation via the internal carotid arteries and the posterior circulation via the vertebral arteries that join to form the basilar artery. The external carotid artery supplies the face and scalp, not brain tissue. The anterior circulation carries the larger share of cerebral blood flow, while the posterior circulation accounts for roughly a third. The vertebral arteries are the primary vessels of that posterior system, so they correspond to about 30% of total brain blood flow. The basilar artery is crucial for posterior circulation as well, but it’s the combined vertebral supply that aligns with that approximate 30% figure.