Which is TRUE about the muscle fibers found in a muscle spindle?
A)They are not true muscle fibers because they cannot contract.
B)They are innervated by alpha motor neurons.
C)They function to maintain tension on spindle receptors.
D)When stimulated to fire,they always inhibit flexor muscles.
E)Their contraction is stimulated by alpha motor neurons and inhibited by gamma motor neurons.

Question

Which is TRUE about the muscle fibers found in a muscle spindle?
A)They are not true muscle fibers because they cannot contract.
B)They are innervated by alpha motor neurons.
C)They function to maintain tension on spindle receptors.
D)When stimulated to fire,they always inhibit flexor muscles.
E)Their contraction is stimulated by alpha motor neurons and inhibited by gamma motor neurons.

Quizplus · Accepted Answer

Muscle spindles contain intrafusal fibers that are indeed true muscle fibers capable of contraction, although their primary function is to maintain appropriate tension on spindle receptors to allow for the detection of changes in muscle length. They are innervated by gamma motor neurons, not alpha motor neurons, which innervate the extrafusal muscle fibers responsible for the muscle's main force of contraction. The role of gamma motor neurons is to adjust the sensitivity of the muscle spindle to stretch, not to inhibit it.

Which Is TRUE About the Muscle Fibers Found in a Muscle