labial sulcus

la·bi·al sul·cus

a furrow between the developing lip and gum. Synonym(s): labiodental sulcus, lip sulcus, primary labial groove

la·bi·al sul·cus

(lābē-ăl sŭlkŭs) Furrow between developing lip and gingiva.
Synonym(s): lip sulcus.