The mechanism behind referred pain involves convergence onto which spinal structure?

• A. Dorsal horn of the spinal cord
• B. Thalamus
• C. Ventral horn
• D. Cerebellum

Answer: (A)

Referred pain comes from convergence of visceral and somatic sensory inputs on the same neurons in the dorsal horn of the spinal cord. Visceral signals from an organ enter the spinal cord and synapse on dorsal horn neurons together with somatic signals from the skin and muscles. Because these inputs share the same first relay in the spinal cord, the brain interprets the signal as coming from a somatic region rather than from the internal organ. The thalamus then relays this information to higher brain areas, but the crucial site that creates the referred sensation is the dorsal horn. The ventral horn is involved with motor output, and the cerebellum is not part of this pain-convergence mechanism.