Spine: S1 radiculopathy motor testing: 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 · Spine: S1 radiculopathy motor testing

Sample item

A 40-year-old with sciatica cannot walk on his toes, has an absent ankle jerk and numbness along the lateral border of the foot. Which nerve root is compressed?

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

The answer and the reasoning

D. S1

The S1 root supplies the gastrocnemius-soleus complex, so toe walking is weak and the ankle jerk is lost, with sensory change over the lateral foot and sole. L5 compression gives weak great toe and ankle dorsiflexion with numbness of the dorsum of the foot. L4 gives a weak knee jerk and medial leg numbness.

Option by option

  • A. L3

    L3 compression affects the quadriceps and anterior thigh.

  • B. L5

    L5 compression weakens extension of the great toe and may cause foot drop.

  • C. L4

    L4 compression reduces the knee jerk and tibialis anterior power.

  • D. S1 (correct)

    Correct. Weak plantarflexion, absent ankle jerk and lateral foot numbness indicate S1.

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, S1. The S1 root supplies the gastrocnemius-soleus complex, so toe walking is weak and the ankle jerk is lost, with sensory change over the lateral foot and sole.

Why is "L3" not the answer?

L3 compression affects the quadriceps and anterior thigh.

Why is "L5" not the answer?

L5 compression weakens extension of the great toe and may cause foot drop.

Why is "L4" not the answer?

L4 compression reduces the knee jerk and tibialis anterior power.

What concept does this question test?

It tests Spine: S1 radiculopathy motor testing in Orthopaedics. L5 compression gives weak great toe and ankle dorsiflexion with numbness of the dorsum of the foot. L4 gives a weak knee jerk and medial leg numbness.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Spine: S1 radiculopathy motor testing?

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.