Which nerve fibers carry messages to the brain and/or spinal cord to produce movement?

• A. Motor
• B. Secretory
• C. Sensory
• D. Mixed

Answer: (A)

Movement happens when the nervous system sends commands from the brain and spinal cord out to the muscles. The nerve fibers that do this are motor (efferent) fibers. They originate in motor neurons in the brain and spinal cord and travel to skeletal muscles, causing them to contract and produce movement.

Sensory fibers, by contrast, carry information from receptors back to the brain and spinal cord and don’t directly cause movement. Secretory fibers control glandular activity, not muscle contraction. Mixed fibers contain both motor and sensory components, so they can carry signals in both directions, but the direct driver of movement is the motor component.