Tetanic contraction, also known as tetanus, is a sustained and prolonged muscle contraction that occurs when a muscle fiber is stimulated rapidly and continuously. This can occur in both skeletal and smooth muscles. Tetanic contractions are stronger and more sustained than single isolated muscle contractions. In skeletal muscle, this occurs when the frequency of stimulation is high enough that the muscle is unable to fully relax between contractions. In smooth muscle, tetanic contractions can occur due to various stimuli such as hormones or neurotransmitters.
