Muscle tone is:

a. the result of voluntary shortening of the muscle.

b. the result of a small amount of involuntary activation of motor units by the nervous system.

c. abnormal—a person's muscles should be relaxed normally.

d. present only where there is damage to the nervous system.

Video transcript

Hi, everyone. Let's take a look at this practice problem together, which of the following acts as a main regulator of muscle tone. The answer options are a muscle fiber B, Endomysium C, motor neuron and D muscle spindle. So recall that muscle tone is defined as the tension in muscle at rest. So what regulates muscle tone? Let's go through the answer. Options together. Option, a muscle fiber recall that this is the term for a single skeletal muscle cell. It does not regulate muscle tone. So option A is incorrect. Option B, Endomysium recall that this is areolar connective tissue and it surrounds each individual muscle fiber. It doesn't regulate muscle tone. However, so option B is also incorrect. Option C the motor neuron, this is a nerve cell that carries action potentials to muscle fibers to produce muscle contraction. However, it does not regulate muscle tone. So option C is also incorrect. The correct answer is the muscle spindle recall that the muscle spindle is a sensory organ with stretch receptors. It is located within skeletal muscles as a stretch receptor. It detects even the most subtle changes in muscle length or stretching. Now, upon detecting a change, it will send signals to the central nervous system. In the central nervous system. The brain processes the signal and can change the level of muscle contraction to maintain the muscle tone. Thus, it's the muscle spindle that is a regulator of muscle tone. So the correct answer is option D muscle spindle. All right, everyone. I hope you found this helpful and I'll see you soon for the next practice problem.