Radius and ulna are bones of the?

The radius and ulna are bones of the lower arm. The lower arm is the part of the upper limb between the elbow and wrist joints. The ulna is located on the side of the arm opposite to the thumb and is slightly longer than the radius. The radius is located on the thumb side of the arm and is shorter than the ulna. The radius and ulna are parallel to each other, and they work together to allow movement of the forearm and hand. The other options listed (pectoral girdle, upper arm, and pelvic girdle) are not related to the bones of the lower arm.