The levator labii superioris is a facial muscle located in the upper lip region of the face. It extends from the infraorbital margin of the maxilla (upper jaw) to the skin of the upper lip and is responsible for elevating and evert the upper lip, exposing the upper teeth. This muscle works together with the zygomaticus minor muscle to produce facial expressions such as smiling, snarling, or sneering. The levator labii superioris muscle is innervated by the zygomatic branch of the facial nerve (cranial nerve VII). It works with other facial muscles to produce a range of facial expressions. Dysfunction or weakness of the levator labii superioris muscle can lead to difficulties with speech, eating, and facial expressions, such as smiling or puckering the lips.