attached to superficial to muscles innervated by the facial nerve orbicularis oris muscle mentalis muscle depressor labii inferioris muscle quadratus labii inferioris depressor of the lower lip UBERON_0001581 A muscle of facial expression, innervated by the facial nerve, attached to the skin of the lower lip, orbicularis oris muscle, and mandible, and superficial and lateral to the mentalis muscle. See Diogo et al., 2009; Burrows et al., 2011) quadratus menti mandible bone lower lip