Gamma motor neurons (γ motor neurons), also called gamma motoneurons, are a type of lower motor neuron that take part in the process of muscle contraction, and represent about 30% of fibers going to the muscle. Like alpha motor neurons, their cell bodies are located in the  anterior horn of the spinal cord. They receive input from the bulboreticular facilitatory region of the pons in the brainstem. Their axons are smaller than alpha motor neurons, with a diameter of only 5 μm. Unlike the alpha motor neurons, gamma motor neurons do not directly adjust the lengthening or shortening of muscles. However, their role is important in keeping muscle spindles taut, thereby allowing the firing of alpha neurons to continue discharging, leading to muscle contraction. These neurons also play a role in adjusting the sensitivity of muscle spindles.