Movement can be produced by reflex circuits in which components of the nervous system?

• A. Only the cerebral cortex
• B. Only the cerebellum
• C. Brainstem and spinal cord
• D. Peripheral nerves only

Answer: (C)

Reflexive movement comes from simple sensorimotor loops that can operate without conscious planning. Those reflex circuits are built into the brainstem and spinal cord. Sensory input from the body travels through peripheral nerves to these centers, and commands to muscles exit via peripheral nerves, but the rapid, automatic response is generated by the neurons in the spinal cord or brainstem themselves. The cerebral cortex handles voluntary, intentional movement and higher decision-making, while the cerebellum helps fine-tune and coordinate movements rather than initiate reflex actions. So reflex-produced movement is primarily supported by the brainstem and spinal cord.