Final answer:
The opposite of pronation is supination, involving the rotation of the forearm that turns the palm forward, with the radius and ulna parallel.
Step-by-step explanation:
The opposite of the motion of pronation, which moves the palm of the hand from the palm forward to the palm backward position, is supination.
Supination is a forearm motion that rotates the palm from a palm backward to a palm forward position. This rotation at the proximal and distal radioulnar joints aligns the radius and ulna into parallel positions once again.
It's helpful to think of supination as the motion you'd use when scooping up soup with a spoon.