Depressor labii inferioris muscle

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

Depressor labii
Muscles of the head, face, and neck.
Originoblique line of the mandible, between the symphysis and the mental foramen
Insertionintegument of the lower lip, Orbicularis oris fibers, its fellow of the opposite side
Nervefacial nerve - Mandibular branch
ActionsDepression of the lower lips
Latinmusculus depressor labii inferioris
Anatomical terms of muscle


This muscle arises from the oblique line of the mandible, and inserts on the skin of the lower lip, blending in with the orbicularis oris muscle. At its origin, depressor labii is continuous with the fibers of the platysma muscle. Much yellow fat is intermingled with the fibers of this muscle.


The depressor labii inferioris is innervated by the mandibular division of the facial nerve.


This muscle helps to depress the lower lip.

See also

Additional images


This article incorporates text in the public domain from page 383 of the 20th edition of Gray's Anatomy (1918)

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