Left and Right M97 are the forewing first basalar muscles. These muscles control the timing of the downstroke of the forewings of the locust. Each spike is a depolarization of the muscle which causes it to contract and depress the wing. When the locust steers, it asymmetrically activates the left and right muscles (Depressor Asymmetry above). This asymmetry shifts the aerodynamic balance of forces acting across the left and right wings allowing the locust to steer.