A 21-year-old patient reports tingling in her thumb during cesarean section under epidural anesthesia. To which dermatomal level would this correspond?

A 21-year-old patient reports tingling in her thumb during cesarean section under epidural anesthesia. To which dermatomal level would this correspond?

• A. C4
• B. C5
• C. C6
• D. C7

Answer: (C)

Dermatomes are skin regions supplied by a single spinal nerve root. The thumb is predominantly in the C6 dermatome, which covers the lateral forearm and the radial side of the hand, including the thumb. If a patient experiences tingling in the thumb during an epidural, this localizes the sensory block to the C6 level. The other options map to different regions (for example, C4 to the shoulder/clavicle area, C5 to the lateral upper arm, C7 to the middle finger), so they don’t explain thumb tingling.

Dermatomes are skin regions supplied by a single spinal nerve root. The thumb is predominantly in the C6 dermatome, which covers the lateral forearm and the radial side of the hand, including the thumb. If a patient experiences tingling in the thumb during an epidural, this localizes the sensory block to the C6 level. The other options map to different regions (for example, C4 to the shoulder/clavicle area, C5 to the lateral upper arm, C7 to the middle finger), so they don’t explain thumb tingling.