Which artery is NOT a part of the cerebral arterial circle (Circle of Willis)?

• A. Anterior cerebral artery
• B. Basilar artery
• C. Internal carotid artery
• D. Posterior communicating artery

Answer: (B)

Verified step by step guidance

1. Step 1: Begin by understanding the anatomy of the cerebral arterial circle (Circle of Willis). It is a ring-like arterial structure located at the base of the brain that provides collateral blood flow between the anterior and posterior circulations of the brain.
2. Step 2: Identify the arteries that are part of the Circle of Willis. These include the anterior cerebral artery, anterior communicating artery, internal carotid artery, posterior cerebral artery, and posterior communicating artery.
3. Step 3: Note that the basilar artery is not part of the Circle of Willis. While it supplies blood to the posterior cerebral arteries, it is located outside the circle and serves as a major vessel connecting the vertebral arteries to the posterior circulation.
4. Step 4: Compare the list of arteries provided in the question to the arteries that are part of the Circle of Willis. The anterior cerebral artery, internal carotid artery, and posterior communicating artery are all part of the Circle of Willis.
5. Step 5: Conclude that the basilar artery is the correct answer because it is not anatomically part of the Circle of Willis, even though it plays a role in supplying blood to the brain.