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UPDATED:The [musculi levator labii superioris alaeque nasi] is one of the superficial muscles of expression found in the face. It is a small bilateral muscle found at the angle of the nose and its function is to elevate the superior lip and the side ("wing") of the nose, slightly opening or "flaring" it. When both of these muscles are activated the facial expression attained is called a "snarl".
Its name is Latin and can be loosely translated as the "muscle that lifts the upper lip and the wing of the nose". The muscle attaches to the superior frontal process of the maxilla and inserts into the skin of the lateral part of the nostril and upper lip.
This muscle has two components, one superficial and the other deep. From the insertion point (see red arrow in accompanying image), the deep muscular fibers insert in the skin of the posterior aspect of the nasal wing. The external muscle fibers cross superficially over the orbicularis oris muscle and insert in the deep skin of the upper lip towards the lip anle.
My friend Dr. Elizabeth Murray calls it "a small muscle with the longest name in human anatomy". Fact is, I think she is right! It is worse in Spanish, where the name of the muscle is "músculo elevador común del ala de la nariz y del labio superior"!
Image modified from the original. Public Domain. "Tratado de Anatomia Humana" Testut et Latarjet 8 Ed. 1931 Salvat Editores, Spain