In an adult, the spinal cord terminates caudally at approximately which level?
- A Lower border of T12 vertebra
- B Lower border of L1 vertebra ✓
- C Lower border of L3 vertebra
- D S2 vertebra
Correct answer: B. Lower border of L1 vertebra
Explanation
The conus medullaris ends at the lower border of the L1 vertebra (some texts say the L1-L2 disc) in the adult, whereas it extends to S1 or lower at birth. Lumbar puncture is therefore performed at the L3-L4 or L4-L5 interspace, well below the cord, within the cauda equina. At birth the cord ends around L3, which is why paediatric taps are done even more caudally.
Reference: Gray's Anatomy for Students, 4th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.