Complications and emergencies: lateral cutaneous nerve of thigh injury: practice question

A Anaesthesia 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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Anaesthesia · Complications and emergencies: lateral cutaneous nerve of thigh injury

Sample item

After a long operation in the lithotomy position with the pelvis tightly strapped, a woman reports burning numbness over the anterolateral thigh. There is no muscle weakness and the knee jerk is normal. Which nerve is affected?

AFemoral nerve trapped under the inguinal ligamentBSciatic nerve stretched by hip flexionCLateral femoral cutaneous nerveDObturator nerve compressed in the obturator canal

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

The answer and the reasoning

C. Lateral femoral cutaneous nerve

The lateral femoral cutaneous nerve is purely sensory and passes under the inguinal ligament near the anterior superior iliac spine, where it can be compressed by tight straps or positioning. The result is meralgia paraesthetica, with burning or numbness over the anterolateral thigh and no motor loss.

Option by option

A. Femoral nerve trapped under the inguinal ligament
Femoral nerve injury would weaken knee extension, abolish the knee jerk and affect the anterior and medial thigh and shin.
B. Sciatic nerve stretched by hip flexion
Sciatic nerve injury causes foot drop or hamstring weakness with sensory loss below the knee, not the anterolateral thigh.
C. Lateral femoral cutaneous nerve (correct)
Correct. A pure sensory loss over the anterolateral thigh with normal power and reflexes fits this nerve.
D. Obturator nerve compressed in the obturator canal
Obturator nerve injury weakens thigh adduction and causes sensory loss on the medial thigh.

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.

Questions about this Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is C, Lateral femoral cutaneous nerve. The lateral femoral cutaneous nerve is purely sensory and passes under the inguinal ligament near the anterior superior iliac spine, where it can be compressed by tight straps or positioning.

Why is "Femoral nerve trapped under the inguinal ligament" not the answer?

Femoral nerve injury would weaken knee extension, abolish the knee jerk and affect the anterior and medial thigh and shin.

Why is "Sciatic nerve stretched by hip flexion" not the answer?

Sciatic nerve injury causes foot drop or hamstring weakness with sensory loss below the knee, not the anterolateral thigh.

Why is "Obturator nerve compressed in the obturator canal" not the answer?

Obturator nerve injury weakens thigh adduction and causes sensory loss on the medial thigh.

What concept does this question test?

It tests Complications and emergencies: lateral cutaneous nerve of thigh injury in Anaesthesia. The result is meralgia paraesthetica, with burning or numbness over the anterolateral thigh and no motor 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 Complications and emergencies: lateral cutaneous nerve of thigh injury?

Make a table of each agent, its key advantage and its main side effect. Then use the flashcards and the other Anaesthesia 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.