Thorax: coronary arteries: 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: coronary arteries

Sample item

A 62-year-old man has an acute anterior myocardial infarction. The next day ECG shows new right bundle branch block with left anterior fascicular block. Which vessel is most likely occluded, and why does it cause this conduction pattern?

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

The answer and the reasoning

C. Left anterior descending artery, whose septal branches supply the right bundle branch and left anterior fascicle

The left anterior descending artery supplies the anterior wall, the apex and the anterior two-thirds of the interventricular septum through septal perforators. These also supply the bundle of His branches, the right bundle branch and the left anterior fascicle. Proximal occlusion producing bifascicular block signals extensive septal damage and a risk of complete heart block.

Option by option

  • A. Posterior descending artery, which supplies the anterior two-thirds of the septum

    The posterior descending artery supplies the posterior third of the septum, not the anterior two-thirds.

  • B. Left circumflex artery, which supplies the anterior septum

    The circumflex artery supplies the lateral and posterior left ventricle, not the anterior septum.

  • C. Left anterior descending artery, whose septal branches supply the right bundle branch and left anterior fascicle (correct)

    Correct. Septal perforators of the left anterior descending artery supply these conduction structures.

  • D. Right coronary artery, whose AV nodal branch supplies the bundle branches

    The right coronary artery supplies the SA and AV nodes in most people, not the anterior bundle branches.

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.

More Anatomy questions

Questions about this Anatomy question

What is the answer to this Anatomy question?

The best answer is C, Left anterior descending artery, whose septal branches supply the right bundle branch and left anterior fascicle. The left anterior descending artery supplies the anterior wall, the apex and the anterior two-thirds of the interventricular septum through septal perforators.

Why is "Posterior descending artery, which supplies the anterior two-thirds o…" not the answer?

The posterior descending artery supplies the posterior third of the septum, not the anterior two-thirds.

Why is "Left circumflex artery, which supplies the anterior septum" not the answer?

The circumflex artery supplies the lateral and posterior left ventricle, not the anterior septum.

Why is "Right coronary artery, whose AV nodal branch supplies the bundle bran…" not the answer?

The right coronary artery supplies the SA and AV nodes in most people, not the anterior bundle branches.

What concept does this question test?

It tests Thorax: coronary arteries in Anatomy. These also supply the bundle of His branches, the right bundle branch and the left anterior fascicle. Proximal occlusion producing bifascicular block signals extensive septal damage and a risk of complete heart block.

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: coronary arteries?

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.