Nerve injuries: anterior 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: anterior interosseous nerve

Sample item

After a supracondylar fracture, a child cannot make the OK sign, with the index tip and thumb tip failing to flex, but sensation is normal. Which nerve is injured?

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

The answer and the reasoning

D. Anterior interosseous nerve

The anterior interosseous nerve is a purely motor branch of the median nerve supplying flexor pollicis longus, the lateral half of flexor digitorum profundus and pronator quadratus. Its paralysis gives the inability to form a circle with thumb and index finger.

Option by option

  • A. Ulnar nerve

    The ulnar nerve causes weakness of adduction and clawing.

  • B. Musculocutaneous nerve

    The musculocutaneous nerve controls elbow flexion.

  • C. Posterior interosseous nerve

    The PIN causes finger drop, not flexion failure.

  • D. Anterior interosseous nerve (correct)

    Correct. Pinch grip failure with intact sensation indicates AIN injury.

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 D, Anterior interosseous nerve. The anterior interosseous nerve is a purely motor branch of the median nerve supplying flexor pollicis longus, the lateral half of flexor digitorum profundus and pronator quadratus.

Why is "Ulnar nerve" not the answer?

The ulnar nerve causes weakness of adduction and clawing.

Why is "Musculocutaneous nerve" not the answer?

The musculocutaneous nerve controls elbow flexion.

Why is "Posterior interosseous nerve" not the answer?

The PIN causes finger drop, not flexion failure.

What concept does this question test?

It tests Nerve injuries: anterior interosseous nerve in Orthopaedics. Its paralysis gives the inability to form a circle with thumb and index finger.

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: anterior 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.