Which structures constitute the central nervous system?

• A. Cranial nerves
• B. Brain and spinal cord
• C. Peripheral nerves
• D. Autonomic nerves

Answer: (B)

The central nervous system is the body's main control center, consisting of the brain and the spinal cord. The brain processes sensory information, thoughts, memory, and controls both voluntary and involuntary actions. The spinal cord relays signals between the brain and the rest of the body and also coordinates reflexes. The other structures listed belong to the peripheral nervous system: cranial nerves branch from the brain to the head and neck, peripheral nerves extend to limbs and organs, and autonomic nerves regulate automatic bodily functions. Therefore, the components that make up the central nervous system are the brain and spinal cord.