Levator labii superioris alaeque nasi is a muscle of facial expression which expands the nostrils and raises the upper lip, therefore helping in making the “sneer” facial expression.
The levator labii superioris alaeque nasi muscle arises via the frontal process of the maxilla.
It separates into three slips:
- Furrow part attaches within the topmost terminal of the nasolabial furrow.
- Alar part attaches within the skin of the posterior terminal of the wing of the nose.
- Lip part attaches constantly within the skin of the upper lip from under the posterior end of the wing of the nose till the lower end of the ridge of the philtrum.
A few long fibers of the lip portion pierce the mass of the orbicularis oris similar to the insertion of the adjacent levator labii superioris.
This slender three-part muscle passes down the side of the nose.
- It is made up of a nasolabial a.k.a. furrow portion, an alar portion, and a lip portion or the long portion.
- The lip portion pegs at the back of the wing of the nose and afterwards emerges inferiorly then on the surface of the orbicularis oris travels inferiorly.
- At this point it arcs medially while constantly attaching within the skin of the upper lip down towards the red portion, as well as within the rim of the philtrum. These particular fibers do not extend towards the center of the philtrum.
The three portions of the levator labii superioris alaeque nasi are located over the nasalis muscle. The furrow portion is situated partially on top of the levator labii superioris as well as may spread out more laterally over the side of the zygomaticus minor.
- The levator labii superioris alaeque nasi elevates:
- The superior end of the nasolabial furrow.
- The posterior end of the wing of the nose.
- The middle portion of each side of the upper lip.
- It only slightly lifts the central part of the upper lip.
- By constant motion but only slightly, it can nearly separate the lips through elevating the mid-part of the upper lip.
- Both sides usually work concurrently, however they can constrict individually.
- It can push the upper eyelid downward.
The zygomatic branches of the facial nerve (CN VII) innervate the levator labii superioris alaeque nasi.