Tone is assessed in the patient's upper limbs by passively flexing and extending the limbs to determine the amount of resistance to the examiner's movements. Increased resistance, such as that in muscle rigidity or spasticity, means increased muscle tone. Decreased resistance, such as that in limpness or flaccidity, means decreased muscle tone. Normal tone has a smooth sensation. In extrapyramidal disease, palpation of a proximal muscle during passive movement detects the presence of cogwheeling, which is a ratchety jerkiness to the motion.
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