The sensitivity of the muscle spindle fiber is controlled by input from
A) Golgi tendon organs.
B) gamma motor neurons.
C) myofibrils.
D) alpha motoneurons.
E) striated muscle fibers.

Question

Quizplus · Accepted Answer

The sensitivity of the muscle spindle fiber is controlled by input from gamma motor neurons, which innervate the intrafusal fibers of the spindle. Activation of gamma motor neurons causes contraction of these fibers, which increases the sensitivity of the spindle to changes in muscle length.

The Sensitivity of the Muscle Spindle Fiber Is Controlled by Input