Neuroanatomy: lumbar puncture: 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 · Neuroanatomy: lumbar puncture

Sample item

A lumbar puncture is performed in the midline of an adult at the L3-L4 interspace. Which is the correct order of structures traversed after the skin and subcutaneous tissue?

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

The answer and the reasoning

B. Supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space, dura mater, arachnoid mater

A midline needle meets the supraspinous ligament joining the spine tips, then the interspinous ligament between the spines, then the tough ligamentum flavum, which gives a loss of resistance as the epidural space is entered. It then pierces the dura and the adherent arachnoid to reach the subarachnoid space. The adult cord ends at L1-L2, so L3-L4 is safe.

Option by option

  • A. Interspinous ligament, supraspinous ligament, ligamentum flavum, epidural space, dura mater, arachnoid mater

    The supraspinous ligament joins the tips of the spines and is met before the interspinous ligament.

  • B. Supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space, dura mater, arachnoid mater (correct)

    This order follows the midline path from the spine tips inward.

  • C. Supraspinous ligament, interspinous ligament, posterior longitudinal ligament, epidural space, dura mater, arachnoid mater

    The posterior longitudinal ligament lies on the back of the vertebral bodies, in front of the canal contents, and is not crossed.

  • D. Supraspinous ligament, ligamentum flavum, interspinous ligament, epidural space, dura mater, arachnoid mater

    The ligamentum flavum lies deep to the interspinous ligament, joining adjacent laminae.

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 B, Supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space, dura mater, arachnoid mater. A midline needle meets the supraspinous ligament joining the spine tips, then the interspinous ligament between the spines, then the tough ligamentum flavum, which gives a loss of resistance as the epidural space is entered.

Why is "Interspinous ligament, supraspinous ligament, ligamentum flavum, epid…" not the answer?

The supraspinous ligament joins the tips of the spines and is met before the interspinous ligament.

Why is "Supraspinous ligament, interspinous ligament, posterior longitudinal…" not the answer?

The posterior longitudinal ligament lies on the back of the vertebral bodies, in front of the canal contents, and is not crossed.

Why is "Supraspinous ligament, ligamentum flavum, interspinous ligament, epid…" not the answer?

The ligamentum flavum lies deep to the interspinous ligament, joining adjacent laminae.

What concept does this question test?

It tests Neuroanatomy: lumbar puncture in Anatomy. It then pierces the dura and the adherent arachnoid to reach the subarachnoid space. The adult cord ends at L1-L2, so L3-L4 is safe.

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 Neuroanatomy: lumbar puncture?

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.