Technology guide
The SMAS: the key layer in non-surgical lifting
The SMAS is the layer the surgeon tightens during a facelift. It is also the layer targeted by HIFU at 4.5 mm. Understanding its role helps explain a sagging jawline and what HIFU can correct.
What is the SMAS?
The SMAS (superficial musculoaponeurotic system) is a thin fibrous and muscular layer located beneath the skin and the superficial fat of the face. It connects the muscles of facial expression to the dermis and continues into the neck as the platysma. It is what "holds" the tissues of the face.
The layers of the face
From the surface to the deeper layers: the very thin epidermis; the collagen-rich dermis; a thin layer of fat; the SMAS; then the muscles and deep structures. Total thickness varies by area, thinner on the forehead, thicker on the cheeks and chin.
What happens with age
The collagen and elastin in the SMAS decrease and deteriorate, the fat pads shrink and the muscles lose tone. The SMAS slackens and no longer lifts back: jowls appear, the cheeks sag, the jawline loses definition and the neck slackens.
How HIFU reaches it
The 4.5 mm head of a HIFU device such as the UltraLift III focuses its heat at the level of the SMAS. The heated fibres contract, then the micro-lesion triggers new collagen production for several weeks: the SMAS firms up and the tissues lift slightly. Priority areas are the jawline, jowls and neck; the temples and eye contour require great caution.
HIFU or surgery?
A surgical facelift physically repositions the SMAS and gives an immediate and lasting result, at the cost of an operation and a recovery period. HIFU suits mild to moderate sagging: a gradual result, with no social downtime, to be maintained with a regular session. For significant sagging, refer to a surgeon.