Depressor labii inferioris muscle

The depressor labii inferioris (or quadratus labii inferioris) is a facial muscle. It helps to lower the bottom lip.

Structure

The depressor labii inferioris muscle arises from the lateral surface of the mandible. This is below the mental foramen, and the origin may be around 3 cm wide.

Function

The depressor labii inferioris muscle helps to depress and everts the lower lip.