Question:easy
Spinal anaesthesia is given at which level?
Spinal anaesthesia is given at which level?
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Inject below the conus medullaris; Tuffier's line marks the L3-L4 space.
Updated On: Jun 24, 2026
- L1-2
- L3-4
- S1
- Midline thoracic segments
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The Correct Option is B
Solution and Explanation
Solve this by deciding where it is both safe and easy to reach the cerebrospinal fluid. The spinal cord itself tapers off around the first or second lumbar vertebra in an adult, so a needle placed higher than that could spear the cord. To stay clear of the cord while still entering the fluid-filled subarachnoid space, the anaesthetist works lower down, at the L3-L4 gap, where only the loose nerve roots of the cauda equina float in the fluid and can simply be brushed aside by the needle. There is also a reliable external guide: a line drawn across the highest points of the two hip bones, known as Tuffier's line, passes over the L4 level or the L3-L4 space, letting the operator find the spot by feel. The other choices fail because L1-2 sits at the cord tip and is risky, S1 is below the typical end of the dural sac, and a thoracic midline approach is simply not how a spinal block is performed. The chosen interspace is therefore L3-L4.\[\boxed{\text{L3-4}}\]
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