levator labiorum

noun1

1. •
   One of the facial muscles that lift the lips, open the mouth, and flare the nostrils.

   • The Occipito Forntalis wrinkles the forehead; the Corrugator Supercilii knits the brow; the Levatores Labiorums lift up the lip, spread wide the nostrils, and open the mouth; […] — 1810