muscle tone

When the physician flexes or extends the joints in a normal, relaxed limb, a certain resistance, known as tone, is detected. This resistance decreases whenever the reflex arc is damaged (usually at the level of the peripheral motor or sensory nerve), but it…

…them taut; this action, called tonic activity, is brought about by discharges in the motor nerve to the muscle. Hence, when the agonist muscle contracts its antagonist must be inhibited.

…receptors is the maintenance of muscle tone (partial contraction) to permit rapid response (fast reaction time) to stimulation. In normal conditions the muscle has tone and is ready to respond; but, when it is without motor stimulation (deafferented), the muscle is flaccid, showing little tone. Upright posture depends on the…

…EEG, intermittent REMs, and suppressed muscle tone. The decrease in muscle tone and a similarly observed suppression of spinal reflexes are indicative of heightened motor inhibition during REM sleep. Animal studies have identified the locus ceruleus (or locus coeruleus), a region in the brainstem, as the probable source of that…