Does a superficial musculoaponeurotic system exist in the face and neck? An anatomical study by the tissue plastination technique.

Abstract

An exact knowledge of the subcutaneous layers in the different regions of the face and neck is important in several surgical disciplines. In the parotid region, a superficial musculoaponeurotic system (SMAS) has been described. The existence of a SMAS as a guiding structure for the surgeon in the other regions of the face and neck has been discussed but is controversial. Therefore, the authors investigated the development of the subcutaneous connective-tissue layers in the different facial regions and in the neck. They studied these regions in 22 human fetuses using the technique of plastination histology and in three newborn and three adult specimens using sheet plastination. In addition, they dissected the neck and face in 10 fresh adult cadavers to identify the SMAS as in the surgical situation. The results show that no SMAS could be detected in any facial regions other than the parotid region. In the parotid region, it is thick and attached to the parotid sheath. However, it becomes very thin, discontinuous, and undissectable in the cheek area. No SMAS can be found in the neck, in which the authors are the first to describe a fascia covering both sides of the platysma. This fascia has close topographical connections to the subcutaneous layers of the adjoining regions. On the basis of these findings, the surgical pathways have to be defined regionally in the face. A "platysma fascia" can be considered as a surgical landmark in the neck. Therefore, the authors conclude that it is not justified to generalize a SMAS as a surgical guiding structure.