Function of muscle spindle is?

Function of muscle spindle is?
a) Movement of a limb
b) Muscle tone maintenance
c) Goal oriented muscle contraction
d) All of the above
Correct Answer - B
Ans. B. Muscle tone maintenance
[Ref Understanding of medical physiology p.138]
If a skeletal muscle is stretched, it respond by contracting.
In other words, if a muscle is stretched, it tends to become shorter
and more stiff, thereby resisting stretch.
This is because of receptor sensitive to stretch within the muscle.
Stretch receptor within a muscle is called “muscle spindles”.
Stretch reflex has two principal functions:

  1. To maintain muscle tone
    Tone is a tendency of a muscle to resist being stretched.
    Muscle tone is not only important for maintaining posture but also
    facilitates locomotion and makes all voluntary movement smooth.
  2. To make muscles respond to stretch and release.