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 face's deep and superficial adipose tissue and has region-specific morphology. Anatomically, the SMAS lies inferior to the zygomatic arch and superior to the platysma's muscular belly.
The fibromuscular layer of the SMAS integrates with the superficial temporal fascia and frontalis muscle superiorly and platysma inferiorly. The SMAS may even be described as a fibrous degeneration of the platysma itself. In reality, a precise anatomical definition of the SMAS is unclear and has been thoroughly debated since Mitz and Peyronie first described this fibromuscular network in 1976.
The SMAS is a key structure involved in facial aging. Understanding the anatomy and dynamics of the SMAS is critical for healthcare providers specializing in facial rejuvenation procedures.
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