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 ...
A muscle spasm — also known as a charley horse, muscle cramp or twitch — is a sudden, involuntary movement in one or more muscles. Common causes include stress, exercise, or dehydration, but nerve ...