Medically reviewed by Katrina Carter, DPT Key Takeaways Voluntary muscles can be controlled by the person, like muscles in your neck and legs. Involuntary muscles work without you thinking about it, ...

DYSTROPHIA myotonica (Steinert's disease) is an uncommon disorder usually characterized by symptoms referable to the voluntary muscles of the head, neck and extremities including difficulty with ...

Sleep myoclonus is involuntary, nonrhythmic muscle twitching that occurs either as a person falls asleep or during sleep. The movements include hiccups, starts, and jerks. Sleep myoclonus is not a ...