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Anatomy

Anatomy and the SMAS

The face is built in layers: skin, fat, the SMAS, a deep fascia and the facial nerve branches beneath it. Facelift techniques differ in which layer the surgeon lifts, which ligaments are released and how close the work runs to the nerve.

Outside to inside

The layers of the face

1. Skin

A lift that tightens only the skin stretches back out. In a modern facelift the deep layer carries the lift and the skin is closed without tension.[1][2]

2. Subcutaneous fat

The fat under the skin sits in separate compartments divided by thin walls, and each ages on its own. The compartments show the surgeon how far to lift the skin and where the cheek has deflated.[1][2][3]

3. SMAS

Mitz and Peyronie named the superficial musculoaponeurotic system in 1976. Cadaver studies find a distinct layer only over the parotid gland and the flat facial muscles, so the SMAS a surgeon lifts is a flap of fat, facial muscle and thin fascia.[1][2][3]

4. Retaining ligaments

Fibrous bands run from bone or deep fascia to the skin and hold the soft tissue in place. Furnas showed in 1989 that the cheekbone and jaw ligaments must be released for the skin to move up fully.[1][2]

5. Facial nerve branches and deep fat

In the cheek the facial nerve branches lie beneath the deep fascia, so a lift that stays above it keeps them covered. Loss of the deep inner cheek fat makes the cheek look dropped and deepens the fold beside the nose.[1][2][3]

The SMAS

The SMAS is the layer of fibrous tissue and muscle under the facial fat, and nearly every facelift by board-certified plastic surgeons tightens it.

Surgeons fold it with stitches, remove a strip of it or lift it as a separate flap. Reviews find high satisfaction with each method, and none has been shown to outperform the others.

In cadavers, lifts that tightened the SMAS raised the face vertically, and a skin-only lift tightened only horizontally.

Plication is the most common method among board-certified plastic surgeons, followed by SMAS flaps.

[1][2][3]

SMAS methods

Ways surgeons handle the SMAS

SMAS plication

The SMAS is folded on itself with stitches and is not lifted off the deeper layer, which keeps the dissection away from the facial nerve.[1]

SMAS imbrication (stacking)

The SMAS is cut, overlapped and sewn, which can add fullness over the cheekbone.[1]

Lateral SMASectomy

A strip of SMAS over the front edge of the parotid gland is removed and the mobile SMAS is sewn to the fixed SMAS behind it.[1][2]

SMAS-platysma flap

The SMAS and the neck muscle are lifted as one flap and advanced.[1][2]

High SMAS

The flap is cut along the cheekbone arch so it lifts the midface, cheek and jawline as one unit.[1][2]

Extended SMAS

The dissection under the SMAS continues forward past the retaining ligaments that tether the cheek.[1]