Final answer:
A supinated grip is when the palm faces forward, not down, in the anatomical stance. Supination and pronation are forearm rotations involving the radius and ulna, with supination moving the palm forward and pronation turning it backward.
Step-by-step explanation:
The statement that a supinated grip would be palms down is incorrect. The correct definition of a supinated position is when the forearm is rotated so that the palm faces anteriorly, which is the palm forward position in the anatomical stance. Supination is the motion used to rotate the forearm to turn the palm to face forward, as if you are holding soup with a spoon, which can help in remembering the term. In contrast, pronation is the motion that moves the palm to face backward. These movements involve the rotation of the radius around the ulna at the radioulnar joints, with supination resulting in the radius and ulna being parallel, and pronation causing these bones to cross and form an X-shape.