Neuroanatomy: circle of Willis: practice question

A Anatomy question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Anatomy · Neuroanatomy: circle of Willis

Sample item

A 60-year-old man has 90% stenosis of the right internal carotid artery and no neurological deficit. Angiography shows the right anterior cerebral artery filling from the left side. Which vessel of the circle of Willis is carrying this flow?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. Anterior communicating artery

The anterior communicating artery joins the two anterior cerebral arteries, so when one internal carotid is stenosed, blood from the opposite carotid can cross to supply the ipsilateral anterior cerebral territory. This collateral explains the absence of symptoms.

Option by option

  • A. Posterior communicating artery

    The posterior communicating artery links the carotid with the posterior cerebral artery, not the two anterior cerebral arteries.

  • B. Anterior communicating artery (correct)

    Correct. It connects the two anterior cerebral arteries.

  • C. Ophthalmic artery

    The ophthalmic artery is a branch of the internal carotid artery and is not part of the circle.

  • D. Basilar artery

    The basilar artery supplies the posterior circulation and does not join the two anterior cerebral arteries.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Anatomy question

What is the answer to this Anatomy question?

The best answer is B, Anterior communicating artery. The anterior communicating artery joins the two anterior cerebral arteries, so when one internal carotid is stenosed, blood from the opposite carotid can cross to supply the ipsilateral anterior cerebral territory.

Why is "Posterior communicating artery" not the answer?

The posterior communicating artery links the carotid with the posterior cerebral artery, not the two anterior cerebral arteries.

Why is "Ophthalmic artery" not the answer?

The ophthalmic artery is a branch of the internal carotid artery and is not part of the circle.

Why is "Basilar artery" not the answer?

The basilar artery supplies the posterior circulation and does not join the two anterior cerebral arteries.

What concept does this question test?

It tests Neuroanatomy: circle of Willis in Anatomy. This collateral explains the absence of symptoms.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Neuroanatomy: circle of Willis?

Learn every nerve by its route, its muscles and what a lesion looks like at the bedside. That one habit answers a large share of questions. Then use the flashcards and the other Anatomy questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.