Postmortem changes: rigor mortis: practice question

A Forensic Medicine 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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Forensic Medicine · Postmortem changes: rigor mortis

Sample item

What biochemical event is responsible for rigor mortis?

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

The answer and the reasoning

B. ATP depletion prevents actin-myosin detachment

After death, ATP production ceases and actin-myosin cross-bridges cannot detach, producing stiffness. Rigor later resolves as proteins break down.

Option by option

  • A. Continued aerobic metabolism

    Aerobic metabolism stops after death.

  • B. ATP depletion prevents actin-myosin detachment (correct)

    Correct. ATP depletion locks the contractile proteins together.

  • C. Uniform blood coagulation

    Coagulation does not cause skeletal muscle stiffness.

  • D. Immediate bacterial gas production

    Putrefactive gas is a later change and does not cause early rigor.

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 Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is B, ATP depletion prevents actin-myosin detachment. After death, ATP production ceases and actin-myosin cross-bridges cannot detach, producing stiffness.

Why is "Continued aerobic metabolism" not the answer?

Aerobic metabolism stops after death.

Why is "Uniform blood coagulation" not the answer?

Coagulation does not cause skeletal muscle stiffness.

Why is "Immediate bacterial gas production" not the answer?

Putrefactive gas is a later change and does not cause early rigor.

What concept does this question test?

It tests Postmortem changes: rigor mortis in Forensic Medicine. Rigor later resolves as proteins break down.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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 Postmortem changes: rigor mortis?

Learn postmortem changes with their timelines, and toxicology as poison, sign, test and antidote. Then use the flashcards and the other Forensic Medicine 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.