The depressor anguli oris is a facial muscle located in the lower part of the face, at the corner of the mouth. It extends from the mandible (lower jaw) to the angle of the mouth and is responsible for pulling the corner of the mouth downward and laterally. This muscle works with the mentalis muscle to produce facial expressions such as frowning, grimacing, or sadness. It also assists in opening the mouth and helps to create facial expressions that convey emotions such as anger, frustration, or disappointment. The depressor anguli oris muscle is innervated by the mandibular branch of the facial nerve (cranial nerve VII) and works in conjunction with other facial muscles to produce a range of facial expressions. Dysfunction or weakness of the depressor anguli oris muscle can lead to difficulties with speech, eating, and facial expressions, such as smiling or puckering the lips.