What is the term for a small, random, irregular twitch in a muscle?

The term "fasciculation" refers to a small, random, and irregular twitch in a muscle. This phenomenon occurs when a bundle of muscle fibers contracts involuntarily, which can be seen or felt under the skin. Fasciculations are often benign and can happen in healthy individuals for various reasons, such as muscle fatigue, stress, or caffeine consumption. They can also indicate underlying neurological issues if they are persistent or widespread.

In contrast, spasm generally refers to a more sustained muscle contraction and is often associated with pain or discomfort. A tremor typically implies a rhythmic, oscillating movement, often involving the hands, and is usually seen in conditions such as Parkinson's disease. Contraction denotes any shortening of muscle fibers to create movement and can be voluntary or involuntary but does not specifically capture the random nature of a fasciculation.