Add Yahoo as a preferred source to see more of our stories on Google. A muscle spasm, also known as a cramp, twitch or charley horse, is the sudden and involuntary forced contraction of a muscle.

Though many people experience muscle twitching, it's often incorrectly identified as a muscle spasm. While both are involuntary contractions of a muscle, muscle spasms and muscle twitching aren't ...

Clonus reflex is a set of rhythmic, involuntary muscle movements. It is a neurological condition that affects the nerve cells that control muscle movements. Damage to the nerves, as in clonus, causes ...

You're relaxing on the sofa when suddenly your eyelid starts twitching. Or perhaps it's a muscle in your arm, your leg, or your foot that begins to spasm—sometimes for a few seconds, sometimes for ...

Muscle cramps are sudden, involuntary contractions that can cause sharp, intense pain lasting from a few seconds to several ...

Q: My cousin was diagnosed with dystonia, what is this? A: Dystonia is a disorder of involuntary muscle contractions that may cause repetitive and/or abnormal movement or postures, for example ...

In a serendipitous discovery, UC San Diego researchers using cryo-EM technology captured the first visualizations of the 3-D structure of the muscle acetylcholine receptor in fetal and adult muscles.