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 ...

Health experts found no cause for a mysterious illness at a Virginia school. Nov. 6, 2007 — -- Virginia school officials plan more testing today to determine the source of a mysterious illness ...