Upper extremities refer to the parts of the body that are located above the waist, including the arms, shoulders, and neck. The antonyms for the term include lower extremities, which refer to the body parts located below the waist, such as the legs and feet. Other antonyms could include the torso, which is the trunk of the body, and the axial skeleton, which includes the skull, spinal column, rib cage, and sternum. While upper extremities are essential for carrying out daily activities, the lower extremities are equally important for walking, running, and maintaining balance.