Levator labii superioris muscle
Levator labii superioris is a short, paired triangular muscle of the face. It belongs to the buccolabial group of muscles of facial expression. This is a broad group of muscles, that besides levator labii superioris also contains levator labii superioris alaeque nasi, zygomaticus major, zygomaticus minor, levator anguli oris, risorius, depressor labii inferioris, depressor anguli oris, mentalis, orbicularis oris, incisivus superior and inferior, and buccinator muscles.
Buccolabial muscles work in synergy to control the shape, posture and movements of the lips. Levator labii superioris contributes to that by elevating the upper lip and thus exposing the maxillary teeth. By performing this action, the muscle helps to produce various facial expressions, such as smiling or disdain.
|Origin||Zygomatic process of maxilla, maxillary process of zygomatic bone|
|Insertion||Blends with muscles of upper lip|
|Action||Elevates upper lip, exposes maxillary teeth|
|Innervation||Zygomatic and buccal branches of facial nerve (CN VII)|
|Blood supply||Facial artery, infraorbital branch of maxillary artery|
This article will discuss the anatomy and function of levator labii superioris muscle.
Origin and insertion
Levator labii superioris originates from the zygomatic process of maxilla and maxillary process of zygomatic bone, just superior to the infraorbital foramen. It courses inferomedially towards the upper lip, gradually tapering and becoming triangular in shape. It inserts between the levator labii superioris alaeque nasi, orbicularis oris and zygomaticus minor by blending with the muscles of the upper lip.
Levator labii superioris fills the bottom of a triangular space bounded laterally by the zygomaticus minor and medially by the levator labii superioris alaeque nasi. Lateral and deep to levator labii superioris is the levator anguli oris. These two muscles bound a narrow interval called the infraorbital tissue space (canine space). This space is clinically significant as it is a predilection site for spreading odontogenic infections.
Levator labii superioris is innervated by the zygomatic and buccal branches of facial nerve (CN VII).
Vascular supply to this muscle is provided by the facial artery and infraorbital branch of maxillary artery.
Together with zygomaticus minor and levator labii superioris alaeque nasi, this muscle is a direct tractor of the upper lip. This means that it inserts to the lip directly, thus acting upon it without the use of an intermediary. By contracting, levator labii superioris helps other buccolabial muscles to elevate and invert the upper lip. This action exposes the maxillary teeth and deepens the nasolabial lines, which has an important function in several facial expressions; smiling, smugness and contempt.