Spinal segments vs Vertebral level

Spinal segment: The part of spinal cord to which a pair of spinal nerves (right and left) is attached.

Cause of mismatch between spinal segments and vertebral level:

  • The spinal cord lags in growth compared to the vertebral column after 3rd embryonic month
  • Spinal cord is shorter (45 cm) compared to the vertebral column (65 cm)
  • Spinal segments always lie above their numerically corresponding vertebral spines
spinal cord segments

General rule:

Vertebral levelAddSpinal segment
Cervical+ 0Same
C7-T1C8
T1-T3+1T1-T4
T3-T6+2T5-T8
T7-T8+3T9-T11
T8-T9T12
T9-T11Lumbar
T12-L1/2Sacral

During clinical examination, when you get any sensory level, always consider this longitudinal discrepancy between cord level and vertebral level.


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