An overview of Superficial Musculo-Aponeurotic System; Anatomic and Radiologic Approach

INTRODUCTION: Superficial musculo aponeurotic system(SMAS) is a network of collagen fibers, elastic fibers and fat interconnecting facial muscles and dermis. Subcutaneous morphology of face is more organized than subcutaneous layer of any part of body. SMAS has distinctive features in forehead, parotid region, zygomatic region, temporal region, cheek, infraorbital region, nasolabial fold, and lower lip. Because SMAS is a key feature for either percutaneous and surgical aesthetic interventions, neurovascular structure embedded in this tissue must be well known.
METHODS: Radiologic views were enrolled from the archive system of radiology department. Random selected images of 50 patients (29 male, 21 female) who underwent MR imaging for any reason were analyzed by the same radiologist who also has PhD degree in anatomy.
RESULTS: Thickness of SMAS for each region was measured. Continuity of the tissue was followed between the junctions of the regions in a proper sequence with MR images. Thickness of SMAS in the zygomatic region was measured in 50 patients and mean value was 0.12 mm. Left and right side measures were compared between genders and no statistical difference between gender groups was found. Correlation between measures and age was analyzed statistically and no correlation was found.
DISCUSSION AND CONCLUSION: A radiologically and clinically neglected tissue: SMAS deserves more attention because of its continuous course interconnecting distinct regions of face and acting as a functional unit for the expressions. Age and gender related changes in SMAS morphology studied in healthy individuals by means of radiology provides an important contribution to the literature.