Thorax: papillary muscles: 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: papillary muscles

Sample item

A 66-year-old man develops acute severe mitral regurgitation 4 days after an inferior myocardial infarction. Echocardiography shows rupture of a papillary muscle. Why is the posteromedial papillary muscle more vulnerable than the anterolateral one?

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

The answer and the reasoning

B. It has a single blood supply from the posterior descending artery

The anterolateral papillary muscle has a dual blood supply from the left anterior descending and left circumflex branches, whereas the posteromedial papillary muscle depends mainly on the posterior descending artery. It is therefore more often ruptured in an inferior infarct. Rupture causes acute pulmonary oedema and a new apical systolic murmur.

Option by option

  • A. It lies in the right ventricle with poor perfusion

    The mitral papillary muscles are in the left ventricle, not the right.

  • B. It has a single blood supply from the posterior descending artery (correct)

    Correct. A single arterial supply makes the posteromedial muscle prone to ischaemic necrosis.

  • C. It receives no collateral flow because it attaches to the septum only

    The posteromedial muscle attaches to the ventricular wall, and its vulnerability is explained by its supply rather than septal attachment.

  • D. It has a dual supply from the left anterior descending and circumflex arteries

    A dual supply from LAD and circumflex describes the anterolateral muscle, which is more protected.

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, It has a single blood supply from the posterior descending artery. The anterolateral papillary muscle has a dual blood supply from the left anterior descending and left circumflex branches, whereas the posteromedial papillary muscle depends mainly on the posterior descending artery.

Why is "It lies in the right ventricle with poor perfusion" not the answer?

The mitral papillary muscles are in the left ventricle, not the right.

Why is "It receives no collateral flow because it attaches to the septum only" not the answer?

The posteromedial muscle attaches to the ventricular wall, and its vulnerability is explained by its supply rather than septal attachment.

Why is "It has a dual supply from the left anterior descending and circumflex…" not the answer?

A dual supply from LAD and circumflex describes the anterolateral muscle, which is more protected.

What concept does this question test?

It tests Thorax: papillary muscles in Anatomy. It is therefore more often ruptured in an inferior infarct. Rupture causes acute pulmonary oedema and a new apical systolic murmur.

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: papillary muscles?

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.