move reflexively

twitch, jerk - make an uncontrolled, short, jerky motion; "his face is twitching"

didder, shake - move with or as if with a tremor; "his hands shook"

shudder, shiver - shake, as from cold; "The children are shivering--turn on the heat!"

move - move so as to change position, perform a nontranslational motion; "He moved his hand slightly to the right"