Which arteries supply the brain and what is the main venous drainage pathway?

• A. The external carotid arteries and vertebral arteries join to form the basilar artery; venous drainage via dural venous sinuses to the internal jugular veins.
• B. The internal carotid arteries and vertebral arteries (which join to form the basilar artery); venous drainage via dural venous sinuses leading to the internal jugular veins.
• C. The anterior cerebral arteries only; jugular veins drain directly to the heart.
• D. The brain is supplied by the coronary arteries.

Answer: (B)

Blood supply to the brain comes from two major arterial systems: the internal carotid arteries and the vertebral arteries. The internal carotids provide the anterior circulation, while the vertebrals—which join to form the basilar artery—provide the posterior circulation. This arrangement, with the basilar artery giving rise to the posterior cerebral arteries and connecting with the anterior circulation through the Circle of Willis, ensures comprehensive perfusion to all brain regions. For venous drainage, brain blood is collected by the dural venous sinuses (such as the superior sagittal, straight, transverse, and sigmoid sinuses), which funnel blood into the internal jugular veins. The external carotid arteries do not supply brain tissue (they serve the face and scalp), and while the anterior cerebral arteries are part of the arterial network, they are not the sole suppliers. The coronary arteries, on the other hand, supply the heart.