(kwah-drā'tŭs lā'bē-ī sū-pēr-ē-ō'ris mŭs'ĕl) Composed of three heads usually described as three separate muscles: the caput angulare, or levator labii superioris alaeque nasi muscle; caput infraorbitale, or levator labii superioris muscle; and caput zygomaticum, or zygomaticus minor muscle. Synonym(s): musculus quadratus labii superioris.