tonic contraction , także: tonic spasm

Tonic contractions are those contractions that are maintained from several minutes up to hours at a time.

(Tonic contractions are also known as tetanic contractions).

Aberrant regeneration of nerve fibers intended for the ciliary muscle causes abnormal, tonic contraction of the pupil with accommodation.

Most insect muscles are phasically responsive (i.e. they contract and relax relatively quickly) but some skeletal and all visceral muscles undergo sustained tonic contractions.

It is important to understand that no action potential is necessary here; the level of entered calcium affects the level of contraction proportionally and causes tonic contraction.

Associated with Edward George Tandy Liddell and Charles Scott Sherrington, the Liddell-Sherrington reflex is the tonic contraction of muscle in response to its being stretched.

A direct comparison of serosal strain gauges to open tipped catheters, however, showed that open tipped tubes detected 87% of all tonic contractions and 80% of all phasic contractions recorded by serosal strain gauges.

Surgery known as GPi DBS (Globus Pallidus Pars Interna Deep Brain Stimulation) has come to be popular in treating phasic forms of dystonia, although cases involving posturing and tonic contractions have improved to a lesser extent with this surgery.

In the bees and the higher Diptera only the indirect muscles of the mesothorax generate the power needed for flight; the metathoracic indirect muscles are capable only of tonic contraction and act so as to control the amount of power transmitted from the mesothorax to the metathorax.