Layer 04, Structural support

SMAS and muscle

The deep architectural layer that supports everything above it.

Depth

The deepest soft-tissue layer above the bone

The SMAS, or superficial musculoaponeurotic system, is a continuous fibromuscular layer that wraps the face and connects the facial muscles to the overlying skin. It is the anatomical layer that surgeons address in a deep-plane facelift, and it is the layer that focused ultrasound technologies are designed to reach non-surgically.

What it is

A fibrous sheet interwoven with the muscles of facial expression. It is continuous with the platysma in the neck and with the temporoparietal fascia in the temples.

The structural framework that transmits muscle movement to the skin and supports the soft tissues of the midface, jawline and neck.

What it does

Provides deep structural support to the face.

Anchors and connects the muscles of facial expression to the overlying skin.

Plays a central role in how the face holds its shape over time.

How it changes with age
  • The SMAS and its attachments may loosen with age, which is associated with descent of the cheeks, deepening of the nasolabial folds and softening of the jawline.
  • Repeated muscle movement, in combination with changes in deeper layers, can contribute to the appearance of established lines.
Categories of treatment that work at this layer
  • Focused ultrasound approaches designed to deliver energy at this depth to stimulate the body's natural tightening response.
  • Neuromodulator categories, which act on the muscle layer to soften dynamic expression lines, considered only after consultation.
Educational content only. This is general information about facial anatomy and is not a recommendation for any specific procedure. Whether any treatment is appropriate for you is determined in a one-on-one medical consultation.

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General information only. Not medical advice. All cosmetic procedures carry risks. A consultation with a registered medical practitioner is required prior to any treatment.