Saturday, 21 January 2012

Jumping Feet (aka: Clonus)

A re-read of some of the HSP pages brings forward a few words that I've not really looked at. Today's word is clonus.

A quick review indicates that clonus is also known as "jumping feet". This sparked off my interest as I recall having "jumping feet" when I was much younger, at junior school, I think. Interestingly there is also myoclonus. Definitions of each are:

Clonus: A form of movement marked by contractions and relaxations of a muscle, occurring in rapid succession, after forcible extension or flexion of a part.

Myoclonus:  A rapid involuntary nonrhythmic spasm that can occur spontaneously at rest, in response to sensory stimulation, or with voluntary movements.

I'm interested to note the similarity of the descriptions between clonus  and myoclonus.

Some links:

The description of clonus on the SP foundation website is: Clonus is an uncontrollable, repetitive jerking of muscles that makes the foot jump rapidly up and down. It occurs when the foot is in a position that causes a disruption of the signals from the brain, leading to an automatic stretch reflex.

This latter description accords with my childhood experience where I was able to make my foot jump up and down when in a sitting position. I cant remember what I did to get it started, but I suppose that because I was able to start this off at will then it makes it forced rather than involuntary.

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