Which statement best describes rigidity?

Which statement best describes rigidity?

• A. Tone increases with faster movement
• B. Muscles have the same stiffness regardless of movement amplitude
• C. Tone is only present during active movement
• D. Rigidity is never accompanied by tremor

Answer: (B)

Rigidity is the presence of increased passive muscle tone that produces a uniform resistance to passive movement throughout the entire range, and it does not depend on how fast or how far you move the limb. The description stating that muscles have the same stiffness regardless of movement amplitude best captures this constant, speed-independent resistance. This contrasts with spasticity, where the resistance increases with faster movement (velocity-dependent). Rigidity is a passive phenomenon and can occur even when the muscle isn’t actively contracting, and in conditions like Parkinson’s disease it can be accompanied by tremor, so it isn’t accurate to say it’s never associated with tremor.

Rigidity is the presence of increased passive muscle tone that produces a uniform resistance to passive movement throughout the entire range, and it does not depend on how fast or how far you move the limb. The description stating that muscles have the same stiffness regardless of movement amplitude best captures this constant, speed-independent resistance. This contrasts with spasticity, where the resistance increases with faster movement (velocity-dependent). Rigidity is a passive phenomenon and can occur even when the muscle isn’t actively contracting, and in conditions like Parkinson’s disease it can be accompanied by tremor, so it isn’t accurate to say it’s never associated with tremor.