Which statement best describes gamma motor neurons?

Which statement best describes gamma motor neurons?

• A. They Increase Spindle Sensitivity
• B. They Innervate Extrafusal Fibers
• C. They Detect Light Touch
• D. They Regulate Blood Flow

Answer: (A)

Gamma motor neurons tune how sensitive the muscle spindle is to stretch. They innervate the contractile ends of intrafusal fibers inside the spindle, causing those fibers to contract and keep the spindle taut as the muscle changes length. This keeps the spindle responsive to even small stretches,so the sense of muscle length and the stretch reflex remain accurate. That’s why the correct statement is that they increase spindle sensitivity. They do not innervate the main force-producing extrafusal fibers (that’s the role of alpha motor neurons), they aren’t receptors for light touch, and they don’t regulate blood flow.

Gamma motor neurons tune how sensitive the muscle spindle is to stretch. They innervate the contractile ends of intrafusal fibers inside the spindle, causing those fibers to contract and keep the spindle taut as the muscle changes length. This keeps the spindle responsive to even small stretches,so the sense of muscle length and the stretch reflex remain accurate. That’s why the correct statement is that they increase spindle sensitivity. They do not innervate the main force-producing extrafusal fibers (that’s the role of alpha motor neurons), they aren’t receptors for light touch, and they don’t regulate blood flow.