Where does the anterolateral pathway cross to the opposite side?

• A. In the Spinal Cord
• B. In the Brainstem
• C. In the Cortex
• D. In the Thalamus

Answer: (A)

Pain and temperature information travel via the anterolateral pathway. After entering the spinal cord, the second-order neurons cross to the opposite side at the ventral white commissure, then ascend on the contralateral side in the spinothalamic tract toward the thalamus and eventually the cortex. The crossing occurs in the spinal cord, not in the brainstem, thalamus, or cortex, which explains why these higher structures receive contralateral input after the decussation. This spinal-level crossing also helps explain clinical patterns of sensory loss after a unilateral spinal cord injury, where pain and temperature become impaired on the opposite side below the lesion.