What all Neoptera share, however, is the way the muscles in the thorax work: these muscles, rather than attaching to the wings, attach to the thorax and deform it; since the wings are extensions of the thoracic exoskeleton, the deformations of the thorax cause the wings to move as well. A set of "dorsal longitudinal muscles" compresses the thorax from front to back, causing the dorsal surface of the thorax (notum) to bow upward, making the wings flip down. A set of "tergosternal muscles" pulls the notum downward again, causing the wings to flip upward.