gamma motor fibre

Gamma motor fibers, also known as gamma efferents, are specialized motor neurons that innervate muscle spindles. These fibers are smaller than the motor axons that control extrafusal muscle fibers and do not cause significant muscle contraction on their own. Their primary function is to regulate the behavior of muscle spindles, which are sensory receptors that provide information about muscle length and changes in length.12

The gamma motor fibers work in conjunction with the muscle spindles to maintain tension within the spindle's operating limits, ensuring the accurate reporting of muscle length to the central nervous system. There are two types of gamma efferents: dynamic and static. Dynamic fusimotor axons increase the sensitivity of the primary ending of the muscle spindle to movement, while static fusimotor axons decrease this sensitivity. This regulation allows the nervous system to fine-tune the muscle spindle's response to external stimuli, playing a crucial role in the precise control of both reflex and voluntary movements.21