Peripheral nerve injuries: obturator 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 · Peripheral nerve injuries: obturator nerve

Sample item

After pelvic surgery for a gynaecological malignancy, a woman has difficulty crossing her legs because she cannot adduct the thigh. She has numbness over the medial thigh. Which nerve is most likely injured?

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

The answer and the reasoning

A. Obturator nerve

The obturator nerve supplies the thigh adductors and a patch of skin over the medial thigh. It runs along the pelvic side wall and is vulnerable during pelvic lymph node dissection. Its injury causes weak adduction, with a tendency for the leg to swing out.

Option by option

  • A. Obturator nerve (correct)

    Correct. Adductor weakness with medial thigh numbness points to the obturator nerve.

  • B. Sciatic nerve

    A sciatic lesion causes weakness below the knee.

  • C. Femoral nerve

    A femoral nerve lesion causes weak knee extension and numbness of the anterior thigh and medial leg.

  • D. Common peroneal nerve

    A common peroneal lesion causes foot drop.

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 A, Obturator nerve. The obturator nerve supplies the thigh adductors and a patch of skin over the medial thigh.

Why is "Sciatic nerve" not the answer?

A sciatic lesion causes weakness below the knee.

Why is "Femoral nerve" not the answer?

A femoral nerve lesion causes weak knee extension and numbness of the anterior thigh and medial leg.

Why is "Common peroneal nerve" not the answer?

A common peroneal lesion causes foot drop.

What concept does this question test?

It tests Peripheral nerve injuries: obturator nerve in Orthopaedics. It runs along the pelvic side wall and is vulnerable during pelvic lymph node dissection. Its injury causes weak adduction, with a tendency for the leg to swing out.

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 Peripheral nerve injuries: obturator 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.