What Is the SMAS?
The SMAS (Superficial Musculoaponeurotic System) is a continuous fibrous layer described by Mitz and Peyronie in 1976. It connects the facial mimetic muscles to the overlying dermis, functioning as an interface between deep and superficial structures. Conceptually, the SMAS can be understood as a facial extension of the cervical platysma. It is continuous with:
- • Superiorly: Galea aponeurotica (scalp)
- • Inferiorly: Platysma (neck)
- • Laterally: Parotid-masseteric fascia
- • Medially: Facial mimetic muscles
💡 Clinical Implication
Being continuous and integrated with mimetic muscles, the SMAS transmits muscular forces to the skin — it’s what creates facial expressions. When we traction the SMAS surgically, we’re moving not just a passive layer, but an entire functional unit.
Fixed SMAS vs Mobile SMAS
This distinction, popularized by Mendelson, is fundamental for surgical planning:
Mobile SMAS
Portion that can be tractioned and repositioned. Primarily located:
- • Over the parotid gland
- • Preauricular region
- • Lateral cheek portion Surgery: This is the portion used for plication, SMAS-ectomy and traction in Deep Plane.
Fixed SMAS
Portion firmly adhered to deep structures by retaining ligaments. Primarily located:
- • Over the zygomatic arch
- • Orbicularis oculi region
- • Parotid-cutaneous line Surgery: Must be released to allow mobilization. Retaining ligaments need to be sectioned. In the context of [Modern Face, this distinction has additional implications: biostimulators often create fibrosis in the mobile SMAS, making sub-SMAS dissection unpredictable. The subperiosteal plane (used in Endomidface) avoids this problem.
Danger Zones: Facial Nerve Mapping The facial nerve (cranial nerve VII) is the most important structure to protect in any facial surgery. Its injury causes motor paralysis with devastating aesthetic and functional consequences.
Basic Facial Nerve Anatomy
The facial nerve emerges from the stylomastoid foramen, traverses the parotid and divides into five main branches (mnemonic: Two Zebras Bit My Cookie):
1. Temporal (frontal): Frontal muscle, superior orbicularis 2. Zygomatic: Orbicularis oculi, lip elevators 3. Buccal: Buccinator, orbicularis oris, nasals 4. Marginal mandibular: Lower lip depressors 5. Cervical: Platysma
Detailed Danger Zones
Location: Structure at risk: Injury consequence: Protection: )) }
Retaining Ligaments: The Key to Facial Ptosis Retaining ligaments are fibrous condensations that anchor the dermis to deep structures. With aging, they weaken, allowing tissues to “fall” — facial ptosis.
Main Retaining Ligaments
Zygomatic Ligament
From zygomatic arch to malar dermis. Its attenuation causes malar ptosis and deepening of the nasolabial fold. Release necessary in Endomidface.
Masseteric Ligament
From anterior masseter border to dermis. Contributes to jowl formation when weakened.
Mandibular Ligament
From mandibular border to dermis. Last support before jowl descends over the mandible.
Platysma-Auricular Ligament
From platysma to auricular region. Important for lateral cervical stability.
🔑 Practical Application — Modern Face
In Endomidface, the zygomatic ligament and orbicularis retaining ligament (ORL) are specifically released to allow vertical elevation of the malar fat pad. In Deep Neck, cervical ligaments are addressed for contour redefinition. The mentorship](/en/blog/what-is-modern-face) teaches safe release of each ligament.
Frequently Asked Questions
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Applied Anatomy in Practice
Mentorship programs include detailed applied anatomy classes with direct correlation between structures and surgical technique.
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