Lower limb: obturator nerve injury: 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 · Lower limb: obturator nerve injury

Sample item

A woman undergoes pelvic lymph node dissection in the obturator fossa. Afterwards she cannot cross one leg over the other, her thigh tends to abduct while walking, and there is numbness over a patch of the medial thigh. Which nerve was injured?

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

The answer and the reasoning

B. Obturator nerve

The obturator nerve (L2 to L4) runs along the lateral pelvic wall, through the obturator canal, and supplies the adductor group and gracilis, with a small cutaneous area on the medial thigh. Injury during pelvic surgery causes weak adduction, an abducted gait and medial thigh sensory loss.

Option by option

  • A. Femoral nerve

    The femoral nerve supplies quadriceps and the anterior thigh, so knee extension would be lost.

  • B. Obturator nerve (correct)

    The obturator nerve supplies the adductors and the skin of the medial thigh.

  • C. Ilioinguinal nerve

    The ilioinguinal nerve supplies the skin of the groin, scrotum or labium and no limb muscles.

  • D. Genitofemoral nerve

    The genitofemoral nerve supplies the skin over the femoral triangle and cremaster, not the adductors.

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.

More Anatomy questions

Questions about this Anatomy question

What is the answer to this Anatomy question?

The best answer is B, Obturator nerve. The obturator nerve (L2 to L4) runs along the lateral pelvic wall, through the obturator canal, and supplies the adductor group and gracilis, with a small cutaneous area on the medial thigh.

Why is "Femoral nerve" not the answer?

The femoral nerve supplies quadriceps and the anterior thigh, so knee extension would be lost.

Why is "Ilioinguinal nerve" not the answer?

The ilioinguinal nerve supplies the skin of the groin, scrotum or labium and no limb muscles.

Why is "Genitofemoral nerve" not the answer?

The genitofemoral nerve supplies the skin over the femoral triangle and cremaster, not the adductors.

What concept does this question test?

It tests Lower limb: obturator nerve injury in Anatomy. Injury during pelvic surgery causes weak adduction, an abducted gait and medial thigh 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 Lower limb: obturator nerve injury?

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.