muscle twitch

A muscle twitch is a small, involuntary contraction of a muscle in response to a brief stimulus. It occurs when nerves send a quick signal to the muscle fibers, causing them to contract briefly before relaxing. This process involves the release of calcium ions within the muscle cells, which allows the fibers to shorten and generate force. Muscle twitches are normal and usually harmless, often happening due to fatigue, stress, or sudden stimuli. They are different from sustained muscle cramps or spasms, as twitches are brief and localized.