Hi,
well, the last definition of "involuntary movement" is not quite right. here's what "Clinical Neurology" by Dr. Frank A. Elliott has to say about involuntary movements: "involuntary movements fall into 7 classes: tremors, athetosis, choreioform movements, clonic spasms, tonic spasms, fasciculations and tics or habit spasms." The brain is certainly not bypassed in any of them, rather they are caused be lesions in different parts of the brain, eg. the corpus striatum, red nucleus, cerebellum, etc.
Spasms are defined as "involuntary, sudden movement or convulsive muscular contraction," and may involve skeletal muscle or visceral (smooth) muscle.
What we usually deal with is spasticity, an increase of tone in muscles due to upper motor neuron lesions.
We also see tremors: fast, rhythmic, alternating contractions of agonists and antagonists.
athetosis: "mobile spasm", consisting of slow, writhing contortions
choreiform movements: quick, jerky and irregular movements in a nonsequential and disorderly manner, without reference to segmental or cortical patterns of movement.
then there are, of course, reflexes.....
Sorry you aked?????????????
neving