fasciculation

This term is primarily used in clinical neurology and anatomy, carrying a highly technical register. In a medical context, it describes the visible twitching of a muscle, which is often benign but can be a diagnostic sign of lower motor neuron disease. It is distinct from a cramp or a seizure, as it involves only a small group of muscle fibers rather than the entire muscle belly.

In anatomical descriptions, the term refers to the structural organization of nerves or muscles into bundles. This usage is descriptive and structural rather than symptomatic, focusing on the morphology of the tissue rather than a physiological event.