Which sign is defined as involuntary oscillatory movement resulting from alternate contractions of muscle groups?

• A. Involuntary oscillatory movement resulting from alternate contractions of muscle groups
• B. Inability to judge distance or range of movement
• C. Broad base of support during gait
• D. Loss of ability to coordinate muscles together for complex movements

Answer: (A)

Tremor is the involuntary, rhythmic movement of a body part produced by alternating contractions of opposite muscle groups. That rhythmic, oscillatory pattern is the defining feature, so this sign best fits. The other options describe different motor signs: dysmetria is the inability to judge distances or movement range, a broad-based gait reflects instability or cerebellar dysfunction, and loss of coordinated muscle action for complex movements describes dyssynergia. None of those capture the characteristic rhythmic oscillation produced by alternating muscle contractions like tremor does.