CLINICAL MEDICINE

Detailed explanation-1: -Therefore a lumbar puncture is generally performed at or below the L3-L4 interspace. As a general anatomical rule, the line drawn between the posterior iliac crests often corresponds closely to the level of L3-L4.

Detailed explanation-2: -Usually, the L2–3, L3–4 and L4–5 levels are preferred for puncture (1, 50). A higher position of the conus may permit performing the puncture at L1–L2.

Detailed explanation-3: -The insertion of a needle under local anaesthetic requires careful positioning to prevent injury to the spinal cord. Since the spinal cord ends as a solid structure around the level of the second lumbar vertebra (L2) the insertion of a needle must be below this point, usually between L3 and L4 (Fig 2).

Detailed explanation-4: -The ideal insertion point of the spinal needle should be either in the interspinous area between L4 and L5 or L3 and L4. Using these landmarks will avoid inadvertent damage to the conus medullaris, which typically terminates at L1.

Detailed explanation-5: -The desired insertion point of the needle is the L3-L4 or L4-L5 interspace; thus, the needle is inserted below the level of the spinal cord. The spinous process of L4 lies along an imaginary line between the top of the posterior superior iliac crests.