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

General rule:

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