Head and Neck Anatomy: Part II – Musculature
Depressor Labii Inferioris

Like many of the muscles of facial expression the depressor labii inferioris does exactly what its name says it should. It acts to depress the lower lip which is the Latin translation of its name. It originates in the anterior mandible along the oblique line. It inserts into the muscular complex of the orbicularis oris on the lower lip.