The levator labii superioris elevates the upper lip and dilates the nostril. Its nasolabial deepening action creates the expression of sadness or disgust. It provides the upper lip fullness visible during speech. Botulinum toxin injection into the levator labii corrects excessive gingival show (gummy smile) by reducing the upper lip elevation that exposes the gum during smiling.
| Origin | Inferior orbital rim (just above the infraorbital foramen) and anterior maxilla |
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| Insertion | Skin and mucosa of the upper lip and lateral alar cartilage of the nose |
| Nerve Supply | Zygomatic and buccal branches of the facial nerve |
| Blood Supply | Angular artery (branch of the facial artery) |
| Actions | Elevates the upper lip; Dilates the nostril (alar component); Produces the nasolabial fold deepening of a genuine upper lip elevation |
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Gummy smile from excessive levator labii and zygomaticus minor activity is corrected by 2-4 units of botulinum toxin injected at the levator labii superioris insertion point 3 mm above the nasolabial fold at the level of the alar base. The effect lasts 3-6 months. Orthognathic surgery (LeFort I impaction) provides permanent correction of skeletal gummy smile.
The levator labii is palpable medial to the zygomaticus major in the cheek, becoming firm during forced upper lip elevation or nostril flaring.
Excessive upper lip elevation exposing more than 3 mm of gum during smiling treated with botulinum toxin injection into the levator labii superioris.
