The Depressor Anguli Oris is a small muscle located at the corners of the mouth. It plays a key role in facial expressions, specifically in lowering the corners of the mouth, which can convey sadness or frowning. This muscle is part of the group known as the facial muscles, which are primarily responsible for facial movements. Anatomically, the Depressor Anguli Oris originates from the mandible, or lower jaw, and inserts into the skin at the corner of the mouth. It is innervated by the facial nerve, which controls most of the muscles of facial expression. Understanding this muscle is important in fields like anatomy, dentistry, and cosmetic surgery.