The muscles innervated by the marginal branch include the depressor anguli oris [depressor anguli oris muscle] (triangularis), depressor labii inferioris [depressor labii inferioris muscle] (quadratus) [quadratus labii inferioris muscle], mentalis [muscle], a portion of the orbicularis oris, and in certain cases, the risorius [risorius muscle] and upper anterior portions of the platysma [platysma muscle].