The levator anguli oris plays a key role in nonverbal communication, as it helps the face form one of the most universally known expressions: the smile.
The muscle elevates the angles of the mouth at each corner. There are two levator anguli oris muscles, each located symmetrically on either side of the mouth. When the two work in unison, the corners of the mouth move upwards. However, many other muscles of the face assist in a smile, and each provides a different level of nuance.
The levator anguli oris arises from the canine fossa, which is located under the infraorbital foramen, an opening in the bone just below the eye socket. The muscle’s fibers insert at the mouth’s angle (corner), and it intermingles with the zygomaticus, triangularis, and orbicularis oris muscles. The levator anguli oris also originates in the maxilla bone (upper jawbone) and inserts into the modiolus, an area in the corner of the mouth that contains eight different muscles.
The muscle receives oxygenated blood from the facial artery, while the buccal branches of the facial nerve provides the sensory innervation.