What is the smaller bone on the thumb side of the lower arm called?

The smaller bone on the thumb side of the lower arm is known as the radius. In the context of human anatomy, the radius and ulna are the two bones that make up the forearm. The radius is located on the lateral side (thumb side) of the forearm when in the standard anatomical position, which is with palms facing forward. It is typically smaller and shorter than the ulna, which is situated on the opposite side of the arm. The radius is crucial for the motion of the wrist and the forearm, allowing for rotational movement.

Understanding these anatomical relationships is important in the field of esthetics, especially in areas involving hand or arm procedures, as knowledge of the underlying structure can inform safe and effective practice. The other options refer to different bones in the body; the fibula is a bone in the lower leg, the humerus is the upper arm bone, and the ulna is the other bone in the forearm, located on the side opposite to the thumb.