Muscle that lifts the lips, General (M. Levator Labiorum Communis)

The levator labii communis (ML), also known as MLK (levator labiorum communis), is a broad muscle of the labial mass involved in lifting the lips and opening the mouth. It is one of the elements of the orbicularis oris muscle, which surrounds the oral cavity and affects facial expression, chewing, swallowing and breathing.

Function The anterior border of the muscle runs along the line of closure of the teeth, separating the mucous membrane of the cheeks in front and the lower lip in the back. In a deeper layer, it continues as the serratus chin muscle and the superficial muscle of the tongue - ligature levatoris. The posterior border extends beyond the border of the lower lip and participates in the formation of two prominent angles. Typically, the muscle lifts the lower lip, slightly pulling it back and giving the face a good-natured or offended expression, depending on the strength of the retraction. Together with the orbicularis oris muscle, the serratus chin muscle, the frontalis muscle and the platysma smile, the platysma moves the lower part of the face upward and posteriorly.

Type of muscle The muscle is supplied by the branch of the mandible of the mental bone (branch of the facial canal) and the inferior labial branch of the submandibular nerve. Electromyographic research shows that the muscle fibers belonging to it are most often excited during chewing and speech. The muscle can be felt by lightly pressing on the lower edge of the lip. Its muscles are much deeper than those of the small muscles, but they also contain connective and smooth muscle bundles, and therefore are able to attach to the floor of the mouth. The concavity of this basal projection allows the muscle to approach the inner surface of the cheeks while the outer surfaces move evenly. When the orbicularis oris muscle contracts, the muscle tissue moves outward along the inside of the cheek, creating a tightening effect on the edges of the lips. Thus, the muscles of the upper lip provide internal protraction of the lower lip, and the muscles of the lower lip provide external protrusion