Muscle tonus

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(1) The muscle in a steady partially contracted state caused by the successive flow of nerve impulses.

(2) The amount of tension or resistance to movement in a muscle.


Muscle tonus helps in maintaining body posture. For instance, the muscles holding the jaw keep it in position with a continuous and partial contraction. When a person sleeps or loses consciousness, the muscle tonus declines.

Word origin: tonus » Greek tónos (tone)


See also: hypotonia, hypertonia.