Which type of nerve fibers carry impulses from the brain to the muscles?

• A. Autonomic nerve fibers
• B. Interneuron fibers
• C. Sensory nerve fibers
• D. Motor nerve fibers

Answer: (D)

Motor nerve fibers are the efferent pathways that carry commands from the brain and spinal cord to skeletal muscles, triggering contraction. They originate in the central nervous system and travel through peripheral nerves to the muscle fibers at the neuromuscular junction, where neurotransmitters like acetylcholine prompt a response. This is how voluntary movements and facial expressions are controlled in cosmetology practices. In contrast, sensory nerve fibers carry information from receptors to the brain, autonomic nerve fibers regulate involuntary muscles and glands, and interneuron fibers connect neurons within the CNS for processing. So the type that carries impulses from the brain to the muscles is motor nerve fibers.