Anatomy, Head and Neck: Eye Levator Anguli Oris Muscle

Excerpt

The levator anguli oris (LAO) is a muscle of facial expression that elevates the mouth's corners (See Image. Levator Anguli Oris). This muscle works with the zygomaticus major and minor, levator labii superioris, and levator labii superioris alaeque nasi to provide upper dental show when smiling and maintain the upper lip's resting tone and position.

While the LAO is not the most critical of the smile muscles, unilateral LAO paralysis can lead to noticeable smile asymmetry, impacting a person's quality of life. Facial reconstructive surgeries involving the upper lip and facial nerve must consider this muscle, which aids in proper speech and mastication while contributing to facial aesthetics. Understanding the LAO's anatomy is essential in treating various cosmetic and functional impairments.