Adrenaline increases the "alertness" of the nervous system, meaning it's ready to trigger muscle contraction. It also increases the amount of blood flow and changes the tension of the muscles, which, ...

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 ...

Muscle twitching is often caused by stress or a lack of sleep and is usually not serious. If muscle twitching occurs with muscle weakness or wasting, you should see a doctor. Muscle twitches can be ...