Which of the following is the correct order of layers pierced during a lumbar puncture?

1. Skin

, 2. Epidural space,

3. Supraspinous ligament,

4. Interspinous ligament,

5. Ligamentum flavum,

6. Subcutaneous tissue,

7. Dura mater,

8. Subarachnoid space. Arrange the correct sequence.

1. A

   1, 4, 2, 6, 5, 8, 7, 3

2. B

   6, 5, 3, 1, 4, 8, 7, 2

3. C

   7, 8, 5, 6, 1, 3, 4, 2

4. D

   1, 6, 3, 4, 5, 2, 7, 8

Appeared in: NORCET 8 Prelims-2025

Explanation

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• The question asks for the correct anatomical sequence of layers a needle passes through during a lumbar puncture, from superficial to deep.
• The correct path starts with the Skin (1), followed by the Subcutaneous tissue (6).
• Next, the needle pierces three ligaments in order: the Supraspinous ligament (3), the Interspinous ligament (4), and the Ligamentum flavum (5).
• After the ligaments, the needle enters the Epidural space (2).
• Finally, it pierces the Dura mater (7) and the arachnoid mater to enter the target Subarachnoid space (8) where cerebrospinal fluid is located.
• This corresponds to the sequence 1, 6, 3, 4, 5, 2, 7, 8.

Why Other Options Were Wrong

• Option A: This option incorrectly places the interspinous ligament (4) before the subcutaneous tissue (6) and the epidural space (2) before the supraspinous ligament (3). The sequence is anatomically incorrect.
• Option B: This option starts with subcutaneous tissue (6) instead of the skin (1), and the overall order of the layers is jumbled and does not follow the superficial-to-deep anatomical path.
• Option C: This option incorrectly starts with the deepest layers, dura mater (7) and subarachnoid space (8), and works outwards. A lumbar puncture proceeds from superficial to deep.

Related Visual

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Anatomy of the spinal column and procedural steps of lumbar puncture as background academic context rather than a clinical decision trigger.
• Understanding the sequence of layers is critical for performing a lumbar puncture safely and successfully. Identifying the 'pop' as the needle passes through the ligamentum flavum helps the practitioner know they are approaching the epidural space.
• Correct needle placement is essential to obtain a clean CSF sample and to avoid complications like a traumatic tap (hitting a blood vessel), nerve root injury, or infection.
• A post-dural puncture headache (PDPH) can occur if the hole in the dura mater does not seal properly, leading to CSF leakage. Knowing the anatomy helps in minimizing trauma to the dura.

How to Approach the Question

• First, identify the core task: arranging the anatomical layers of a lumbar puncture in the correct order.
• Recall the anatomy of the spine from the most superficial layer (skin) to the deepest target layer (subarachnoid space).
• Mentally list the layers: Skin -> Subcutaneous tissue -> Supraspinous ligament -> Interspinous ligament -> Ligamentum flavum -> Epidural space -> Dura mater -> Arachnoid mater -> Subarachnoid space.
• Match the numbered items in the question to your recalled anatomical list: Skin (1), Subcutaneous tissue (6), Supraspinous ligament (3), Interspinous ligament (4), Ligamentum flavum (5), Epidural space (2), Dura mater (7), Subarachnoid space (8).
• Form the correct numerical sequence: 1, 6, 3, 4, 5, 2, 7, 8.
• Compare your sequence with the given options to find the correct match.

Concept Tested & Keywords

• Concept Tested: Anatomy of the spinal column and procedural steps of lumbar puncture.
• Stem keywords: lumbar puncture, layers pierced, correct order, sequence
• Lead-in keywords: Arrange the correct sequence

Question ID

QC-OZKeHcaDNOOv7PyiTFD

Copy ID

Reference Book

E6 Anatomy Applied Ashalatha 4e p. 423-425