Head and Neck Anatomy: Part II – Musculature
Depressor Anguli Oris

With the depressor anguli oris we finally have a muscle that is involved in frowning. This muscle originates along the inferior border of the mandible and inserts at the corner of the mouth. Unlike the other muscles we have discussed that insert at that spot this one is attached inferiorly so depresses the corner of the mouth resulting in a frown rather than a smile.