In 1980 Alberca et al. described a patient with a syndrome of increased muscle irritability, who presented ondulating muscle rolling movements and electrically silent cramps, myoedema and muscle reactions to mechanical stimulation similar to myotonic response, suggesting a disfunction at myofibrillar level.
For c-3po, it was a costume, Anthony Daniels played c-3po: For R2-D2, It was a costume and a remote controlled robot. CGI was also used in the prequel trilogy. So, they had Kenny Baker to play him : And from Portrayal section of wookieepedia article on R2-D2 :
He quickly became a fan-favorite character and maintained that status through the duration of the series. Many years before LOST was even an idea, Terry OâQuinn played Malcolm Engle in The Dare, S9/E4. This is my favorite Matlock episode of all time, involving some interesting twists from the normal format.