Motor fibers are specialized nerve fibers that transmit signals from the central nervous system to muscles. These signals enable voluntary movements, such as walking or grasping objects, by instructing muscles to contract or relax. There are two main types of motor fibers: alpha motor neurons, which control large muscle groups, and gamma motor neurons, which regulate muscle tone. Together, they play a crucial role in coordinating movement and maintaining posture, ensuring that the body can respond effectively to various physical demands.