Uh-oh, someone made a mistake, you make that face of surprise and pull your lower lip down. If you didn’t have the Depressor Labii Inferioris muscle, then you wouldn’t be able to do this expression.

This muscle is part of the facial muscles that by itself doesn’t make much but acting together with other muscles, it creates a broad range of facial expressions involving the lips and lower part of the face.

General Information about the Depressor labii inferioris muscle

Another name for the Depressor Labii inferioris muscle is quadratus labii inferioris muscle.

What does the Depressor Labii Inferioris Muscle do?

The Depressor labii inferioris functions as a tractor of the lower lip. In other words, it acts upon the lower lip and inserts into it as well. When contracted, the Depressor Labii Inferioris action plays a role in facial expression by pulling the lower lip down and to the midline, helping create an expression of doubt, sadness and nervousness.

The antagonist muscle to the depressor labii inferioris is the Orbicularis Oris.

Botox injections on the Depressor Labii inferioris

Botox is used on this muscle to get a more youthful contour of the face. However, given the complex nature of the anatomical structures, sometimes there are undesirable effects, such as in this article, where her smile was asymmetrical and she couldn’t laugh.

Depressor Labii Inferioris

Innervation

Facial nerve (VII)

Blood Supply

• Ophtalmic Artery
• Zygomatico-orbital artery
• Angular artery

Muscle Attachments

Depressor Labii Inferioris origin

• Frontal bone
• Medial palpebral ligament
• Lacrimal bone

Depressor Labii Inferioris Insertion

Lateral palpebral raphe

References

Standring, Susan. Gray’s Anatomy: The Anatomical Basis of Clinical Practice. , 2016. Print.