clon-, clono-, clonus-

(Greek > Medical Latin: muscle spasm; to move violently; turmoil)

ankle clonus, foot clonus
A series of abnormal reflex movements of the foot, induced by sudden dorsiflexion, causing alternate contractions and relaxations of the triceps surae muscle.
1. Relating to abnormal neuromuscular activity characterized by rapidly alternating muscle contraction and relaxation.
2. A reference to clonus; alternately contracting and relaxing the muscles.
Referring to the condition of alternately, contracting, and relaxing the muscles.
Both clonic and tonic, as some forms of muscular spasm.
clonism, clonismus
A state of successive clonic contractions or a reference to the phase of an epileptic convulsion or the type of movement occurring in this phase, usually in the form of brief muscular contractions repeated at short, regular intervals.
An instrument for registering, or recording, the movements in clonic spasm.
Rapid alternation of muscular contraction and relaxation.

The rate is much slower than a tremor. In upper motor neuron paralysis, sharp flexion of the ankle often produces ankle clonus.

1. A form of movement marked by contractions and relaxations of a muscle, occurring in rapid succession.
2. A continuous rhythmic reflex tremor initiated by the spinal cord below an area of spinal cord injury, set in motion by reflex testing.
3. Spasmodic alternation of muscular contractions between antagonistic muscle groups caused by a hyperactive stretch reflex from an upper motor neuron lesion.

Usually, sustained pressure, or stretch of one of the muscles, inhibits the reflex.

An extended clarification about clonus

The term clonus is a succession of intermittent muscular relaxations and contractions, usually resulting from a sustained stretching stimulus.

An example is the clonus stimulated in the calf muscle by maintaining sustained upward pressure on the sole of the foot. The condition is often a sign of disease in the brain or spinal cord.

—Based on information from
Black's Medical Dictionary, 41st Edition;
Edited by Dr. Harvey Marcovitch; The Scarecrow Press, Inc.;
Lanham, Maryland; 2005; page 145.
grand mal seizure (s) (noun), grand mal seizures (pl)
1. A type of epilepsy or a brain disorder in which clusters of nerve cells, or neurons, in the brain sometimes signal abnormally; resulting in the loss of consciousness, generalized muscle contractions, urinary incontinence, tongue biting and a condition with confusion and lethargy following the cessation of the stroke: Linda was subject to grand mal seizures which presented a risk for her pregnancies; so, she was frequently hospitalized during the months prior to giving birth to each of her children.

Some grand mal seizures may last for just a few seconds or they can continue for several minutes.

2. Etymology: from French grand mal, "big illness" and is an antonym of another type of epilepsy known as petit mal, "little illness".

logoclonia, logoklony
1. Spasmodic repetition of the end, or last, syllables of words.
2. Reiterative utterances of parts of words; reported frequently in Alzheimer disease.
patellar clonus
A rhythmic jerking movement of the patella ("kneecap" or the small bone that is in the front of the knee) produced by grasping it between the thumb and the forefinger and pushing it suddenly and forcibly toward the foot.

This is an abnormal reflex with alternate contractions and relaxations of the quadriceps muscle (great extensor muscle of the knee, forming a large fleshy mass which covers the front and sides of the femur or thigh bone).

1. A condition in which a sound is heard on auscultation over a muscle, indicating fibrillary contractions that may be so fine that they are not seen when visually inspected.
2. Clonic spasms of muscles in response to aural stimuli.
3. The intermittent sound that may be heard when a stethoscope is applied to the skin over a muscle afflicted by myoclonic jerks.
tonoclonic, tonicoclonic
Both tonic and clonic; said of a spasm or seizure consisting of a convulsive twitching of the muscles.

a. Tonic: Producing and restoring the normal tone; characterized by continuous tension.

b. Clonic, clonus: A form of movement marked by contractions and relaxations of a muscle, occurring in rapid succession.

wrist clonus
Spasmodic contraction of the hand muscles, induced by forcibly extending the hand at the wrist.

Don't confuse this clon- group with another clon- unit meaning "exact duplicate, replica".