Final answer:
Clonus is a flapping motion caused by alternating activation of antagonistic stretch reflexes. Reflexes can be based on deep stimulation of tendons or superficial stimulation of the skin. The presence of reflexive contractions helps differentiate motor disorders between the upper and lower motor neurons.
Step-by-step explanation:
Clonus is a flapping motion caused by alternating activation of antagonistic stretch reflexes. Reflexes can be based on deep stimulation of tendons or superficial stimulation of the skin. The presence of reflexive contractions helps differentiate motor disorders between the upper and lower motor neurons. Hypertonia, accompanied by hyperreflexia (excessive reflex responses), often results from damage to upper motor neurons in the CNS.