Spine: far lateral disc herniation: 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: far lateral disc herniation

Sample item

A 45-year-old has severe anterior thigh pain, quadriceps weakness and a diminished knee jerk. MRI shows a disc fragment lying within the neural foramen at L4-L5, with the central canal clear. Which root is compressed?

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

The answer and the reasoning

A. The exiting L4 root

A foraminal or far lateral herniation compresses the root that is leaving at that level, which is L4 at the L4-L5 disc. This causes quadriceps weakness, medial leg sensory change and a reduced knee jerk. A paracentral herniation at the same disc would instead catch the traversing L5 root.

Option by option

  • A. The exiting L4 root (correct)

    Correct. A foraminal fragment at L4-L5 catches the exiting L4 root, matching the quadriceps weakness and reduced knee jerk.

  • B. The traversing L5 root

    The L5 root is traversing and is hit by a paracentral herniation, causing great toe weakness rather than quadriceps weakness.

  • C. The S1 root

    The S1 root causes a reduced ankle jerk and weak plantar flexion.

  • D. The cauda equina

    Cauda equina compression needs a large central herniation and causes saddle anaesthesia and sphincter loss.

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, The exiting L4 root. A foraminal or far lateral herniation compresses the root that is leaving at that level, which is L4 at the L4-L5 disc.

Why is "The traversing L5 root" not the answer?

The L5 root is traversing and is hit by a paracentral herniation, causing great toe weakness rather than quadriceps weakness.

Why is "The S1 root" not the answer?

The S1 root causes a reduced ankle jerk and weak plantar flexion.

Why is "The cauda equina" not the answer?

Cauda equina compression needs a large central herniation and causes saddle anaesthesia and sphincter loss.

What concept does this question test?

It tests Spine: far lateral disc herniation in Orthopaedics. This causes quadriceps weakness, medial leg sensory change and a reduced knee jerk. A paracentral herniation at the same disc would instead catch the traversing L5 root.

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: far lateral disc herniation?

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.