Final answer:
A muscle twitch is the response to a single stimulus above threshold, resulting in an increase in muscle tension through a latent, contraction, and relaxation phase.
Step-by-step explanation:
The development of tension in a muscle, in response to a single stimulus above threshold, is called a muscle twitch. This phenomenon includes three phases: a latent period where the action potential is being propagated, a contraction phase when tension increases due to cross-bridge formation, and a relaxation phase where tension decreases as calcium ions are reabsorbed and cross-bridge cycling stops.
A muscle twitch is different from tetanus, which is the continuous contraction of muscles due to a high frequency of stimuli leading to the fusion of multiple twitches.