Thorax: collateral circulation in coarctation: 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 · Thorax: collateral circulation in coarctation

Sample item

A 14-year-old boy with hypertension in the arms and weak femoral pulses has notching of the inferior borders of the ribs on a chest radiograph. Which collateral route carries blood past the aortic narrowing?

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

The answer and the reasoning

A. Subclavian to internal thoracic to anterior intercostal to posterior intercostal arteries to descending aorta

In post-ductal coarctation the proximal aorta supplies the lower body by collaterals. The subclavian arteries feed the internal thoracic arteries and their anterior intercostal branches, which anastomose with the posterior intercostal arteries and flow backwards into the descending aorta. The dilated, tortuous posterior intercostal arteries erode the lower borders of ribs, producing rib notching.

Option by option

  • A. Subclavian to internal thoracic to anterior intercostal to posterior intercostal arteries to descending aorta (correct)

    Correct. This chain runs through the intercostal arteries and causes rib notching.

  • B. Superior mesenteric to inferior mesenteric artery through the marginal artery

    The mesenteric arcade connects branches below the narrowing and does not bypass a thoracic coarctation.

  • C. Internal iliac to external iliac arteries through the obturator artery

    The iliac collaterals lie below the narrowing and do not bypass it.

  • D. Coronary to bronchial arteries through the pulmonary trunk

    Coronary and bronchial arteries do not provide a bypass for the descending aorta.

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 A, Subclavian to internal thoracic to anterior intercostal to posterior intercostal arteries to descending aorta. In post-ductal coarctation the proximal aorta supplies the lower body by collaterals.

Why is "Superior mesenteric to inferior mesenteric artery through the margina…" not the answer?

The mesenteric arcade connects branches below the narrowing and does not bypass a thoracic coarctation.

Why is "Internal iliac to external iliac arteries through the obturator artery" not the answer?

The iliac collaterals lie below the narrowing and do not bypass it.

Why is "Coronary to bronchial arteries through the pulmonary trunk" not the answer?

Coronary and bronchial arteries do not provide a bypass for the descending aorta.

What concept does this question test?

It tests Thorax: collateral circulation in coarctation in Anatomy. The subclavian arteries feed the internal thoracic arteries and their anterior intercostal branches, which anastomose with the posterior intercostal arteries and flow backwards into the descending aorta. The dilated, tortuous posterior intercostal arteries erode the lower borders of ribs, producing rib notching.

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 Thorax: collateral circulation in coarctation?

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.