Levator labii superioris

At a glance

English

Levator labii superioris

Latin (TA2)

Levator labii superioris

System

Muscle

Region

Head

Side

Paired, left and right

About the levator labii superioris

As a muscle of facial expression, the levator labii superioris works in the upper lip region, lying between the nose and the cheek. In older accounts it was described as a broad sheet, the quadratus labii superioris, with three heads stretching from beside the nose across to the zygomatic bone. Modern terminology treats these heads as three separate muscles: levator labii superioris alaeque nasi medially, the levator labii superioris proper in the middle, and the zygomaticus minor laterally. On this page the term refers mainly to the middle, infraorbital head.

That head springs from the lower rim of the orbit just above the infraorbital foramen, partly from the maxilla and partly from the adjoining zygomatic bone. Its fibres run down and converge into the muscle of the upper lip, ending between levator labii superioris alaeque nasi on the inner side and the levator anguli oris on the outer side, which lies deeper. The infraorbital nerve and vessels emerge from their foramen beneath it, so it covers them on the face. The medial head, from the top of the maxilla's frontal process, splits into slips to the nostril and the lip, and the lateral head arises from the outer face of the zygomatic bone behind the zygomaticomaxillary suture and slants down and in to the lip.

The main action of the muscle is to raise the upper lip and turn it slightly outwards, uncovering the upper teeth. Working with its neighbours it deepens the upper part of the nasolabial fold and contributes to expressions of sadness, contempt and disgust as well as to smiling. It is supplied by the buccal and zygomatic branches of the facial nerve and receives blood from the facial artery and the infraorbital artery.

In facial palsy the upper lip on the affected side hangs lower and the nasolabial fold flattens. The muscle also marks the place where an infraorbital nerve block is given, as the needle is aimed at the foramen beneath it.

Attachments, action and supply

Origin

Lower margin of the orbit just above the infraorbital foramen, from the maxilla and zygomatic bone.

Insertion

Upper lip musculature, between levator labii superioris alaeque nasi and the levator anguli oris.

Action

Elevates and slightly everts the upper lip.

Nerve supply

Buccal and zygomatic branches of the facial nerve (cranial nerve VII).

Blood supply

Facial artery and infraorbital artery.