As I am laying in bed, remembering all of season 4 since I last watched it months back. I came to ask myself. How was Yangs arm attached? Obviously some form of base was placed on where her arm was severed. But how were the muscles connected for the arm to respond to Yang? Was the process similar to Full metal Alchemists automail connection where its extremely painful? Or was it an easy process due to Atlas' advaced technology in such practices?