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 correct sequence follows the anatomical path from the most superficial layer (skin) to the deepest target layer (subarachnoid space).
• The needle first pierces the skin (1) and subcutaneous tissue (6).
• It then passes through a series of ligaments: the supraspinous (3), interspinous (4), and ligamentum flavum (5).
• After the ligamentum flavum, the needle enters the epidural space (2).
• Finally, it pierces the dura mater (7) and the underlying arachnoid mater to enter the subarachnoid space (8) to access cerebrospinal fluid.

Why Other Options Were Wrong

• Option A: This sequence is incorrect. For example, it places the interspinous ligament (4) before the subcutaneous tissue (6) and supraspinous ligament (3).
• Option B: This sequence is incorrect. It starts with subcutaneous tissue (6) and places the skin (1) fourth, which is anatomically impossible.
• Option C: This sequence is incorrect as it starts from the deepest layers (dura mater and subarachnoid space) and works outwards, which is the reverse of the needle's path.

Related Visual

• Visual 1: Diagram - A sagittal view of the lumbar spine showing a needle passing through the sequential layers from the skin to the subarachnoid space. Each layer should be clearly labeled to match the items in the question.

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Anatomical sequence of layers in lumbar puncture as background academic context rather than a clinical decision trigger.
• A lumbar puncture is a common diagnostic and therapeutic procedure used to obtain cerebrospinal fluid (CSF), measure CSF pressure, or administer medications (like spinal anesthesia).
• Nurses play a crucial role in positioning the patient (lateral decubitus or sitting with spine flexed), maintaining a sterile field, monitoring the patient during the procedure, and providing post-procedure care.
• Post-procedure care includes monitoring for complications like a post-lumbar puncture headache (caused by CSF leakage), which is managed by having the patient lie flat, ensuring adequate hydration, and administering analgesics.

How to Approach the Question

• First, identify the question type. This is a sequencing question that requires knowledge of anatomy.
• Read the list of structures and mentally visualize the layers of the back, moving from the outside (skin) inward towards the spinal cord.
• Start with the most superficial layer, which is always the skin (1), followed by the subcutaneous tissue (6). This immediately narrows down the possible correct options.
• Recall the order of the ligaments: the supraspinous ligament (3) is most superficial, followed by the interspinous ligament (4), and then the ligamentum flavum (5) just before the epidural space.
• Finally, remember the order of the spaces and meninges: epidural space (2), dura mater (7), and then the target subarachnoid space (8).
• Assemble the sequence of numbers based on this anatomical path (1, 6, 3, 4, 5, 2, 7, 8) and match it to the given options.

Concept Tested & Keywords

• Concept Tested: Anatomical sequence of layers in lumbar puncture
• Stem keywords: lumbar puncture, layers pierced, correct order, sequence
• Lead-in keywords: Arrange the correct sequence

Question ID

QC-OZKeHcaDNOOv7PyiTFD

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