What is the arterial circle that connects the brain's anterior and posterior blood supplies?

• A. Basilar Artery
• B. Internal Carotid Artery
• C. Anterior Cerebral Artery
• D. Circle of Willis

Answer: (D)

The Circle of Willis is the arterial circle that links the brain’s anterior and posterior blood supplies. It sits at the base of the brain as a ring formed by connecting arteries: the anterior communicating artery ties the two anterior cerebral arteries, while the posterior communicating arteries link the internal carotid system to the posterior cerebral arteries, which arise from the basilar artery. This arrangement bridges the anterior circulation (supplied by the internal carotid arteries) with the posterior circulation (supplied by the basilar artery), providing a pathway for collateral blood flow if one route narrows or is blocked. The other arteries listed are important parts of the circulation, but they do not form the connecting ring itself.