A twitch is a small, involuntary contraction and relaxation of a muscle or group of muscles. Medication side effects, physical exertion, fatigue, and excessive caffeine can all cause twitching in the ...

Muscle twitches fall into two main types. There’s myoclonus, where a whole muscle or group of muscles twitch or spasm. Then ...

Infectious agents can cause muscle twitching and spasms, too. The most commonly known is probably tetanus, which causes a phenomenon called lockjaw, where the neck and jaw muscles contract to the ...

Tweaked by a muscle twitch? From an uncontrollable fluttering eyelid to a pulsing calf muscle, these small, rapid involuntary muscle contractions may happen at any time -- and can be annoying. A ...