Which of the following nerve supply platysma?

Cervical branch of facial nerve supplies platysma. Platysma takes its origin from the fascia covering the pectoralis major and the deltoid. It passes upwards superficial to the clavicle and it spread out as a thin sheet in the superficial fascia of the neck. Anterior fibers inse into the base of mandible. Posterior fibers cross the mandible and inse into the modiolus at the angle of mouth and into the lower lip. Action: It acts by depressing the mandible and draws the angle of mouth in the inferior direction.