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.
Details
Origin	oblique line of the mandible, between the symphysis and the mental foramen
Insertion	integument of the lower lip, Orbicularis oris fibers, its fellow of the opposite side
Nerve	facial nerve - Mandibular branch
Actions	Depression of the lower lip
Identifiers
Latin	musculus depressor labii inferioris
TA98	A04.1.03.033
TA2	2083
FMA	46816
Anatomical terms of muscle

Structure

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.

Innervation

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

Actions

This muscle helps to depress the lower lip.

See also

• Facial muscles
• Depressor anguli oris

Additional images

• 
  Position of depressor labii inferioris muscle (red).
• 
  Mandible. Outer surface. Side view.

References

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