Which structure relays messages from the cerebral cortex to the spinal cord?

• A. Cerebral cortex
• B. Midbrain
• C. Medulla oblongata
• D. Pons varoli

Answer: (D)

Messages from the cerebral cortex that control voluntary movement travel down the corticospinal tract through the brainstem and into the spinal cord. The key relay point to the spinal cord is the medulla oblongata, where the pyramidal decussation occurs and most corticospinal fibers cross to the opposite side. From there, the fibers continue as the lateral and anterior corticospinal tracts to reach spinal neurons and produce coordinated movements.

The pons (pons varoli) mainly serves as a bridge connecting the cortex with the cerebellum via the pontine nuclei, so it relays information to the cerebellum rather than acting as the primary conduit to the spinal cord. The midbrain has other motor and sensory roles, but it is not the main relay for cortical messages to the spinal cord. The cerebral cortex is the source of these signals, not the relay station.