The superficial musculoaponeurotic system in the upper lip: an anatomic study in cadavers.

Ten cadavers were employed to demonstrate the presence of the SMAS in the upper lip using macroscopic and microscopic techniques. The relationships and attachments of the SMAS to the dermis of the upper lip are described. In cadavers, medial traction on the SMAS in the upper lip in conjunction with superolateral traction on the SMAS in the cheek is found to decrease the depth of the nasolabial fold. Superior traction on the SMAS in the upper lip elevates the interlabial line, reestablishes the convexity of the lateral vermilion border, and partially increases concavity of the profile.