During pain signal transmission, which neuron crosses the midline within the spinal cord?

During pain signal transmission, which neuron crosses the midline within the spinal cord?

• A. First Order Neuron
• B. Second Order Neuron
• C. Third Order Neuron
• D. Fourth Order Neuron

Answer: (B)

The signal-crossing step in pain transmission is handled by the second-order neuron. After the peripheral nociceptors (first-order neurons) bring the pain signal into the spinal cord and synapse in the dorsal horn, the second-order neuron sends its axon across the midline at the level of the ventral white commissure. This decussation puts the contralateral side in charge of processing that pain as it travels up the spinothalamic tract to the thalamus. From there, the third-order neurons carry the signal to the somatosensory cortex for conscious perception. The first-order neuron doesn’t cross at this stage, and there isn’t a standard fourth-order neuron in this pathway.

The signal-crossing step in pain transmission is handled by the second-order neuron. After the peripheral nociceptors (first-order neurons) bring the pain signal into the spinal cord and synapse in the dorsal horn, the second-order neuron sends its axon across the midline at the level of the ventral white commissure. This decussation puts the contralateral side in charge of processing that pain as it travels up the spinothalamic tract to the thalamus. From there, the third-order neurons carry the signal to the somatosensory cortex for conscious perception. The first-order neuron doesn’t cross at this stage, and there isn’t a standard fourth-order neuron in this pathway.