Hypertonia is a condition marked by an abnormal increase in muscle tension and a reduced ability of a muscle to stretch. It is caused by lesions to upper motor neurons in the central nervous system, which carry information from the central nervous system to the muscles and control posture, muscle tone, and reflexes. When the injury occurs in children under the age of 2, the term cerebral palsy is often used. Damage to the central nervous system results in the loss of control of motor neurons and gives rise to disordered spinal reflexes, increased excitability of muscle spindles and decreased synaptic inhibition
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