Superficial Fascia in the Cheek and the Superficial Musculoaponeurotic System.

Abstract

The origins and validity of the term "superficial musculoaponeurotic system" (SMAS) is reviewed. Gray stated the superficial fascia connects the skin with the deep or aponeurotic fascia and consists of fibro-areolar tissue. Hollinshead wrote superficial fascia exists throughout the body and contains a variable amount of fat. In the head and neck, it encloses voluntary muscles in its deep portion. Skoog found superficial fascia was fixed to the dense, deep fascia by fibrous adhesions in the temporal, preauricular, and parotid area. Mitz stated "There is a 'superficial muscular and aponeurotic system' (SMAS) in the parotid and cheek areas." SMAS has an intimate relationship with the entire superficial fascia of the head and neck and divides the subcutaneous fat into 2 layers. Wassef found a continuous fibromuscular layer at the deep limit of the "subcutis," which corresponded to the "superficial fascia." Nakajima reported the subcutaneous adipofascial tissue was made up of 2 adipofascial layers. Macchi found 2 different fibroadipose connective layers bounded to the laminar connective tissue layer (SMAS). In the cheek, Hwang found horizontal fibrous connective tissues (membranous layer of superficial fascia) divided the superficial fascia into the superficial fatty layer and the deep fatty layer. Recently, Mitz explained the reason for the term SMAS. The "musculo+aponeurotic" component is based on histology of muscle cells, including the risorius, in the same structure to be surgically consistent. The aponeurotic cells belong to the same surgical layer. SMAS is not sufficient to replace the old term "superficial fascia" of the cheek area.