The term "torso" in the anatomy of the body designated person without head and arms. In art, this notion implies a sculpture of a naked human body parts without limbs.
First, a word torso designated surviving fragments of ancient marble sculptures that have no head and hands. Inspired by the works of the ancient Greeks, the sculptors of the XIX century began to develop the theme of torsos in his art. Under the "torso" is meant only part of the body without limbs, so the portrait sculptures use the term "bust".