Anatomy, Skin, Superficial Musculoaponeurotic System (SMAS) Fascia

In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan.


The superficial musculoaponeurotic system, or SMAS, is often described as an organized fibrous network composed of the platysma muscle, parotid fascia, and fibromuscular layer covering the cheek. This system divides the deep and superficial adipose tissue of the face and has region-specific morphology. Anatomically, the SMAS lies inferior to the zygomatic arch and superior to the muscular belly of the platysma.

The fibromuscular layer of the SMAS integrates with the superficial temporal fascia and frontalis muscle superiorly and with the platysma muscle inferiorly. The SMAS is even often described as a fibrous degeneration of the platysma muscle itself. In reality, a precise anatomical definition of the SMAS is unclear and has been thoroughly debated since its first description by Mitz and Peyronie in 1976.

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