Final answer:
The Levator Anguli Oris is a facial muscle that elevates the corners of the mouth, contributing to smiling and enhancing nasolabial creases. It works with other facial muscles like the orbicularis oris and the buccinator muscles, which help in articulating expressions and maintaining the oral cavity's functions.
Step-by-step explanation:
The Levator Anguli Oris is a muscle of facial expression that lies beneath the skin at the corners of the mouth. This muscle is responsible for elevating the angle of the mouth, contributing to expressions such as smiling. When the Levator Anguli Oris contracts, it pulls the corners of the mouth upwards and laterally. It plays a significant role in facial expressions by working in conjunction with other muscles, such as the orbicularis oris which encircles the mouth and regulates the flow of what comes in and goes out of the mouth. The facial markings that are enhanced or formed by the Levator Anguli Oris include the nasolabial creases, which become more pronounced when one smiles.
Furthermore, the orbicularis oris muscle is surrounded by various other facial muscles that assist with different movements and expressions involving the lips and mouth. The cheeks are mainly constituted by the buccinator muscles, lying between the skin and mucous membranes, which also aid in keeping food within the mouth while chewing. This illustrates the complex interplay of muscles within the facial structure that are essential for daily activities such as eating, speaking, and expressing emotions.