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Lumbar epidural needle anatomy — FRCA Primary MCQ

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ModerateAnatomyLumbar epidural needle anatomyFRCA Primary

A 29-year-old woman in labour receives epidural analgesia. The needle passes through skin, subcutaneous tissue, supraspinous ligament and interspinous ligament before loss of resistance is obtained. Which structure is traversed immediately before the epidural space by a midline approach?

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Correct answer: A — Posterior longitudinal ligament

In a midline lumbar epidural approach, the ligamentum flavum is traversed immediately before the epidural space. Dura mater lies beyond the epidural space and is punctured during spinal anaesthesia or accidental dural puncture. The longitudinal ligaments are closely related to the vertebral bodies rather than the posterior midline approach. The teaching point is that the ligamentum flavum often provides the tactile change used for loss of resistance.

Reference: RCoA Primary FRCA Syllabus 2026; Anatomy for Anaesthetists