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 ...

Many of us have felt a muscle in some part of our body suddenly and involuntarily tighten, causing a twitch or even severe cramp. Muscle spasms are common and typically don't signal a severe health ...