Clonus

Under a clonus (from Greek: klonos, " violent movement " ) is defined as involuntary, rhythmic contractions of muscles or muscle groups. (See a spasm )

Synonymous with the term " clonic spasm " used.

Pathophysiology

The clonus is a sort of extreme form of a tendon reflex dar. It is triggered by a stretching stimulus, for example, by passive stretching of a joint. The strain stimulus is perceived via the muscle spindles and forwarded via afferent nerve fibers to the spinal cord. There he is monosynaptically connected in the reflex arc of a motor neuron and finally back played over efferent fibers as an excitation to the muscle.

This process is usually mediated by fibers of the pyramidal tract. When clonus this control is defective, so that instead of the physiological properties reflex occurring, short excitation takes place a continuous excitation of the muscle. The clonus is therefore a pyramidal tract signs.

After the duration of clonus, one can distinguish two forms:

• Unerschöpfbarer clonus
• Exhaustible clonus (only for pathological side difference )