Lower limb: sciatic nerve: 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: sciatic nerve

Sample item

For foot surgery, an anaesthetist injects local anaesthetic around the nerve about 8 cm above the popliteal crease so that both the tibial and common peroneal components are blocked with one injection. What anatomical fact makes this possible?

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

The answer and the reasoning

C. The sciatic nerve is still one trunk there, dividing usually near the apex of the popliteal fossa

The sciatic nerve leaves the pelvis below piriformis and runs down the back of the thigh as a single trunk with tibial and common peroneal parts. It usually divides at or near the apex of the popliteal fossa, so a proximal popliteal block reaches both.

Option by option

  • A. The sciatic nerve always divides high at the greater sciatic foramen

    High division occurs in a minority of people and is not the usual rule that makes the block reliable.

  • B. The sural nerve is the main trunk at that level

    The sural nerve is a purely sensory branch arising below the popliteal fossa.

  • C. The sciatic nerve is still one trunk there, dividing usually near the apex of the popliteal fossa (correct)

    Correct. A common trunk proximal to its usual division allows one injection to block both parts.

  • D. The tibial and common peroneal nerves arise separately from the femoral nerve

    These nerves come from the sciatic nerve, and the femoral nerve supplies the anterior 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.

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Questions about this Anatomy question

What is the answer to this Anatomy question?

The best answer is C, The sciatic nerve is still one trunk there, dividing usually near the apex of the popliteal fossa. The sciatic nerve leaves the pelvis below piriformis and runs down the back of the thigh as a single trunk with tibial and common peroneal parts.

Why is "The sciatic nerve always divides high at the greater sciatic foramen" not the answer?

High division occurs in a minority of people and is not the usual rule that makes the block reliable.

Why is "The sural nerve is the main trunk at that level" not the answer?

The sural nerve is a purely sensory branch arising below the popliteal fossa.

Why is "The tibial and common peroneal nerves arise separately from the femor…" not the answer?

These nerves come from the sciatic nerve, and the femoral nerve supplies the anterior thigh.

What concept does this question test?

It tests Lower limb: sciatic nerve in Anatomy. It usually divides at or near the apex of the popliteal fossa, so a proximal popliteal block reaches both.

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: sciatic nerve?

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.