Risorius

The risorius is a very slender and relatively narrow facial muscle located lateral to the mouth, overlying the buccinator. It is a superficial muscle and a component of the superficial musculoaponeurotic system (SMAS). Because of its lateral position, the risorius pulls the angle of the mouth outward, enabling smiling and laughing. Due to this function, it is often referred to as the “smiling muscle.”