Parotid fascia and face lifting: a critical evaluation of the SMAS concept.

Classical anatomists were mistaken in their description of the parotid and masseteric regions. According to their description, the fascia superficialis (or SMAS) would be in continuity with the platysma. Data from fresh cadaver dissections, histology, and embryology indicate, on the contrary, that it is the parotid fascia, which is continuous with the platysma. Comparative anatomy provides further confirmatory evidence, demonstrating that the parotid fascia is only the uppermost part of a muscle that has undergone fibrous degeneration. This muscle is the "primitive" platysma. In consequence, the sub-SMAS dissection plane is too superficial and creates a purely fatty flap. Conversely, deep dissection below the parotid fascia (and therefore below the primitive platysma) respects the true anatomic features and guarantees the solidity of the flap and the safety of the facial nerve.