Referred pain occurs because the brain misinterprets visceral input as coming from which area?

• A. The skin region corresponding to the organ's spinal segment
• B. The organ itself
• C. The opposite side
• D. The brainstem

Answer: (A)

Referred pain happens because visceral sensory input is processed by the same spinal neurons that receive somatic (skin) input from a particular skin area called a dermatome. The brain uses that somatic map to interpret pain signals, so when visceral nerves enter at a given spinal level, the pain is felt in the skin region served by that level rather than in the organ itself. In other words, the brain mistakes the visceral signal for coming from the skin area corresponding to the organ’s spinal segment. For example, heart-related pain is often felt in the chest and left arm because those skin areas share the same spinal segments as the heart’s visceral nerves.