QS Study

Muscle tone is a state of partial contraction of muscle due to an asynchronous discharge of motor nerve supplying the muscle. It is the continuous and passive partial contraction of the muscles or the muscle’s resistance to passive stretch during resting state

Receptor: muscle spindle

Regulation of muscle tone

Part of CNS concerned with the regulation of muscle tone.

Fig.: Regulation of muscle tone

Mechanism of regulation

  • Tonic α-motor neuron discharge.
  • Contraction of intrafusal muscle fiber of muscle spindle
  • Distorting the anulospiral endings and set up of receptor potential.
  • Action potential.
  • Afferent impulses through anulospiral fiber as well as flower spray fiber.
  • Via dorsal root ganglia into spinal cord.
  • Efferent impulse through the lower motor neuron.
  • Contraction of extrafusal muscle fiber is proportional to a motor activity and acts as long as the activity casts.
  • Muscle tone is maintained.

Importance of muscle tone

  1. It sets the basis for efficient willed movement.
  2. It sets the basis for the efficiencies of the reflex action.
  3. It is also responsible for maintenance of posture.
  4. It also helps in maintenance of form; texture and appearance eg., look of the subject.

Cause of abolishing at muscle tone

  • By destroying the center in the spinal cord.
  • By destroying the posterior root,
  • By destroying the anterior root,
  • By division of the peripheral nerve entering a muscle.
  • By transaction of the spinal cord.
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