What is the SMAS in facelift surgery?

The SMAS, which stands for superficial musculo-aponeurotic system, is a layer of fat and muscle tissue just under the surface of the skin on the face. Modification of the SMAS is the main component of most facelift surgery, not just the skin. Long-lasting facelift results are obtained by lifting and tightening the SMAS through a variety of techniques.