Final answer:
The statement is true; in anatomical position, the radius is lateral and the ulna is medial in the forearm, connected by an interosseous membrane.
Step-by-step explanation:
The statement that the radius is lateral and the ulna is medial in the forearm when in anatomical position is true. In anatomical position, the upper limbs are held next to the body with the palms facing forward. This is considered a supinated position. In this orientation, the radius is indeed located on the lateral side (thumb side) of the forearm, while the ulna is on the medial side (closer to the body's midline). The two bones are connected via an interosseous membrane, and during movements like supination and pronation, they interact to allow rotation of the forearm.