(1) the groove between the maxillary and mandibular halves of the labial vestibule; (2) in the embryo, the groove formed by the deepening of the labial sulcus; its inner wall becomes incorporated with the alveolar process of the mandible or the maxilla, and its outer wall with the lips and cheeks. SYN: alveololabial sulcus, gingivolabial groove, gingivolabial sulcus.
