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 :
The film was written and directed by Tom McLoughlin. Although the original concept called for Tommy Jarvis, the protagonist of parts IV and V, to become the new villain, the poor fan reception of Friday the 13th Part V: A New Beginning prompted the producers to bring back Jason Voorhees as the series' antagonist.