muscle tone

Examples of muscle tone in the following topics:

• Muscle Tone

  • Muscle tone is a measure of a muscle's resistance to stretching while in a passive resting state.
  • Muscle tone is controlled by neuronal impulses and influenced by receptors found in the muscle and tendons.
  • The main regulator of muscle tone is the muscle spindle, a small sensory unit that is closely associated with and lies parallel to a muscle.
  • If tone decreases and the muscle stretches the spindle, an impulse results in a muscle contraction.
  • Muscle tone ensures that even when at rest the muscle is at least partially contracted.

• Abnormal Contractions of Skeletal Muscle

  • Involuntary muscle contractions are referred to as spasms, and can be due to abnormal activity of the nerve or the muscle.
  • In medicine, a spasm is a sudden, involuntary contraction of a muscle, a group of muscles, or a hollow organ, or a similarly sudden contraction of an orifice .
  • Examples of spasms include muscle contractions due to abnormal nerve stimulation, or abnormal activity of the muscle itself.
  • In this case, the hypertonic muscle tone is excessive and the muscles are unable to relax.
  • Hypertonic muscle spasms is the state of chronic, excessive muscle tone, or tension in a resting muscle – the amount of contraction that remains when a muscle is not actively working.

• Muscular Atrophy

  • People with sedentary jobs and senior citizens with decreased activity can lose muscle tone and develop significant atrophy.
  • Astronauts, free of the gravitational pull of Earth, can develop decreased muscle tone and loss of calcium from their bones following just a few days of weightlessness.
  • disease of the muscle itself.
  • Muscles, primarily voluntary muscles, become progressively weaker.
  • In some types of muscular dystrophy, heart muscles, other involuntary muscles and other organs are affected.

• Aging and the Digestive System

  • Aging can result in changes of the digestive system due to decreased nerve sensitivity, loss of muscle, and increased infection rate.
  • The changes associated with aging of the digestive system are largely caused by decreased nerve sensitivity, loss of muscle tone, and increased susceptibility to bacterial infection because of a weakened immune system.
  • Thus, changes include loss of strength and tone of muscular tissue and supporting muscular tissue, decreased secretory mechanisms, decreased motility of the digestive organs, along with changes in neurosensory feedback regarding enzyme and hormone release, and diminished response to internal sensations and pain.

• Benefits of Stretching

  • Stretching is a form of physical exercise, where specific skeletal muscles are stretched, improving elasticity and muscle tone.
  • Stretching is a form of physical exercise in which a specific skeletal muscle (or muscle group) is deliberately stretched, often by abduction from the torso, in order to improve the muscle's felt elasticity and reaffirm comfortable muscle tone.
  • Stretching can strengthen muscles, and in turn strong muscles are important to stretching safely and effectively.
  • Other research concludes that active stretching routines will reduce muscle-tendon viscosity and increase muscle compliancy and elasticity.
  • This may cause muscle injury in individual performance.

• Hypotonia and Hypertonia

  • Hypertonia is the reduced ability of muscles to stretch due to increased muscle tension; hypotonia, due to chronic reduced muscle tension.
  • Hypertonia is a reduction in the ability of a muscle to stretch due to increased muscle tension; it is caused by lesions to upper motor neurons.
  • Effects of hypertonia include spasticity dystonia (a state of prolonged muscle contractions) and rigidity (a state of muscle stiffness and decreased flexibility).
  • Hypotonia is the state of reduced muscle tone and tension, resulting in lessened ability to generate force from muscle contractions.
  • A muscle spindle, with γ motor neurons, sensory fibers and proprioceptor that detect the amount and rate of change of length in a muscle.

• Local Regulation of Blood Flow

  • Arterioles contain smooth muscle fibers in their tunica media which allows for fine control of their diameter.
  • Local responses to stretch, carbon dioxide, pH, and oxygen also influence smooth muscle tone and thus vasoconstriction and vasodilation.
  • However, the arterioles of skeletal muscle, cardiac muscle, and the pulmonary circulation vasodilate in response to these hormones acting on beta-adrenergic receptors.
  • Generally, stretch and high oxygen tension increase tone, and carbon dioxide and low pH promote vasodilation.
  • A number of hormones influence arteriole tone such as the vasoconstrictive epinephrine, angiotensin II and  endothelin and the vasodilators bradykinin and prostacyclin.

• Uterine Prolapse

  • The uterus is normally held in place in the lower pelvis by a hammock of muscles and ligaments called the pelvic floor.
  • These include insufficient muscle tone and asymmetries caused by trauma to the pelvis, age, pregnancy, family history, and hormonal status.
  • Surgery can be performed to repair pelvic floor muscles, or the uterus can be removed in a surgery known as a hysterectomy.

• Assessing CNS Disorders

  • Cranial nerves (I-XII): sense of smell (I), visual fields and acuity (II), eye movements (III, IV, VI) and pupils (III, sympathetic and parasympathetic), sensory function of face (V), strength of facial (VII) and shoulder girdle muscles (XI), hearing (VII, VIII), taste (VII, IX, X), pharyngeal movement and reflex (IX), tongue movements (XII).
  • Muscle strength, often graded on the MRC scale 0 to 5 (i.e. 0 = Complete Paralysis to 5 = Normal Power).
  • Rigidity-Cogwheeling (abnormal tone suggestive of Parkinson's disease), Gegenhalten (resistance to passive change, where the strength of antagonist muscles increases with increasing examiner force.

• Muscles of the Shoulder

  • As suggested by the name superficial muscles lie on the surface, there are two superficial extrinsic muscles.
  • The muscle converges into a tendon attaching to the humerus.
  • Three deep muscles lie below the superficial muscles of the shoulder.
  • Deltoid – The deltoid muscle is a triangular muscle which covers the shoulder.
  • The rotator cuff is a group of four muscles which utilize muscle tone to pull the ball of the humerus into the shallow socket of the scapula, adding required stability.