Extreme decreases in muscle tone are described as what term?

• A. Hypotonicity
• B. Hypertonicity
• C. Isotonicity
• D. Dystonia

Answer: (A)

Hypotonia describes extreme decreases in muscle tone, meaning there is much less resistance to passive movement and the muscles feel unusually soft or floppy. This reflects reduced baseline motor neuron activity or impaired pathways that normally help maintain muscle tension. Clinically, it presents as limbs that move with little effort, joints that are unusually lax, and sometimes delayed motor development in infants.

This is different from hypertonicity, where there is increased resistance to passive movement and stiffness. Dystonia is a movement disorder with sustained or repetitive muscle contractions causing abnormal postures, often linked to abnormalities in tone as well but not simply a low-tension state. Isotonicity isn’t used to describe tone; it relates to muscle contraction under a constant load, not the resting tone level.