Nerve injuries: posterior interosseous nerve: practice question

A Orthopaedics 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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Orthopaedics · Nerve injuries: posterior interosseous nerve

Sample item

A man with a Monteggia fracture-dislocation has finger drop but can extend the wrist, with radial deviation, and has no sensory loss. Which nerve is injured?

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

The answer and the reasoning

C. Posterior interosseous nerve

The posterior interosseous nerve is a deep motor branch of the radial nerve and can be injured with radial head dislocation or compressed at the arcade of Frohse. Extensor carpi radialis longus is spared, so wrist extension remains with radial deviation. There is no sensory loss.

Option by option

  • A. Median nerve

    A median nerve lesion would not cause finger drop.

  • B. Radial nerve at the axilla

    A high radial lesion would give wrist drop and sensory loss.

  • C. Posterior interosseous nerve (correct)

    Correct. Finger drop with preserved wrist extension and no sensory loss points to the PIN.

  • D. Anterior interosseous nerve

    The AIN does not control extension.

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 Orthopaedics question

What is the answer to this Orthopaedics question?

The best answer is C, Posterior interosseous nerve. The posterior interosseous nerve is a deep motor branch of the radial nerve and can be injured with radial head dislocation or compressed at the arcade of Frohse.

Why is "Median nerve" not the answer?

A median nerve lesion would not cause finger drop.

Why is "Radial nerve at the axilla" not the answer?

A high radial lesion would give wrist drop and sensory loss.

Why is "Anterior interosseous nerve" not the answer?

The AIN does not control extension.

What concept does this question test?

It tests Nerve injuries: posterior interosseous nerve in Orthopaedics. Extensor carpi radialis longus is spared, so wrist extension remains with radial deviation. There is no sensory loss.

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 Nerve injuries: posterior interosseous nerve?

Pair each fracture with its classic complication and nerve injured. Then use the flashcards and the other Orthopaedics 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.