Which bones make up the lower arm?

The lower arm, anatomically known as the forearm, is primarily made up of two long bones: the radius and the ulna. These bones run parallel to each other between the elbow and the wrist. The radius is located on the lateral side of the forearm (the thumb side) and is involved in the wrist movements, especially during pronation and supination of the forearm. The ulna, on the other hand, is positioned on the medial side (the side closest to the body) and provides stability to the forearm and serves as a point of articulation with the humerus at the elbow.

The other choices involve bones not located in the forearm. The humerus is the bone of the upper arm, while the scapula and clavicle are part of the shoulder girdle. Carpals and metacarpals are the bones found in the wrist and hand. Therefore, the radius and ulna are the definitive answer when considering the composition of the lower arm.