In electromyography, which response indicates a normal muscle at rest?

In electromyography (EMG), a normal muscle at rest is characterized by electrical silence. This means that there is no spontaneous electrical activity detected in the muscle fibers when they are not being contracted. This absence of activity is indicative of a healthy, resting muscle, as any electrical activity during rest may suggest neuromuscular abnormalities or irritability within the muscle.

Spontaneous potentials can indicate various conditions such as denervation, myopathies, or other neuromuscular disorders. Polyphasic potentials, which reflect multiple motor unit contributions, typically appear during muscle contraction rather than at rest. Occasional motor unit potentials, while observable in some cases, could indicate pathology if present at rest. Thus, electrical silence serves as the correct indicator of a normal muscle resting state in electromyography.