Levator labii superioris alaeque nasalis muscle

Levator labii superioris alaeque nasalis (LLSAN) muscle is traditionally thought of as a muscle of the mouth, but is also a crucial muscle of the nose, a subset of the muscles of facial expression ¹. 

Summary

• origin: maxilla, nasal bone, medial canthus
• insertion: nasal base
• innervation: facial nerve (VII)
• action: depressor of the tip of the nostril

Gross anatomy

Origin

• its fibers originate from the frontal process of the maxilla, nasal bone, and medial canthus (of the eye)

Insertion

• its muscle fibers pass inferiorly as two main components
  • alaris
    • fibers pass into the superior margin of the lower lateral nasal cartilage and skin of the alar base, intermingling with the dilator naris muscle
  • labiocolumellaris (a.k.a. labial portion)
    • fibers pass around the nasal base and into the philtrum, ramifying with myrtiformis and, then into the columella, joining with orbicularis oris fibers

Arterial supply

• infraorbital artery (branch of the maxillary artery) ²
• facial artery

Venous drainage

• facial vein

Innervation

• zygomatic and buccal nerves (branch of facial nerve (VII))​

Action

• alaris: elevator and dilator of the nostril
• labiocolumellaris: depressor of the nostril tip

Variant anatomy

The levator labii superioris alaeque nasalis muscle is one of the more consistent muscles of facial expression, it was found without difficulty in a surgical study of forty-five cadavers ¹.