Continuing medical education article—facial aesthetic surgery: Why do we age in our cheeks?

Abstract

The cheeks are of one of the first regions of the face in which changes relating to age occur and are the facial area most prone to ultimately display the ravages of time. The purpose of this study was to determine (1) the subcutaneous fat mass in the cheeks both above and below the superficial musculoaponeurotic system (SMAS) relative to the facial and neck aesthetic subunits, and (2) the type and distribution of retaining ligament support of this subcutaneous fat mass within the cheeks relative to other aesthetic subunits. Anatomic dissections in 10 fresh hemi-cadavers with a mean age of 65.6 years (range 42-86 years) were performed. The face and neck were divided into 8 aesthetic subunits: (1) glabella, (2) forehead, (3) temporal, (4) anterior upper cheek, (5) middle cheek, (6) posterolateral cheek, (7) mental, and (8) anterior neck. The dermis was discarded, and fat superficial to the SMAS in each aesthetic subunit was dissected, measured in grams, and analyzed. Superficial mimetic musculature was discarded, and fat deep to the SMAS in each subunit was dissected, measured in grams, and analyzed. The retaining ligament types and distribution were dissected and analyzed within each aesthetic subunit. Histologic cross-sectional analysis of fat and fascia was performed in each aesthetic subunit by hematoxylin and eosin staining and Mason Trichrome Sections. Overall, 80% of total subcutaneous fat mass was found in the face and 20% in the neck. In the face, 57% of the fat mass was found above the SMAS, and 43% was found below the SMAS, whereas in the neck 65% of the fat mass was found above the platysma and 35% below the platysma. One half of the total face and neck fat mass was found in the cheeks, with one third of the total fat mass located in the anterior and middle cheeks alone. Of special note, 75% of the total deep facial fat mass was found in the anterior and middle cheeks. Two types of retaining ligaments were found. Primary supporting ligaments were found in 4 locations approximating the zygomatic and mandibular sutural interfaces. These ligaments only resided along borders between cheek aesthetic subunits and were observed to be mildly affected by cadaver age. Secondary supporting ligaments were found in 3 locations within the anterior, middle, and posterior cheek subunits. They were found only within borders of the cheek aesthetic subunits and were observed to be significantly affected by cadaver age. The anterior, middle, and posterior cheeks were noted to be laden with fat, containing roughly half of the total facial and neck fat mass in fresh human cadavers dissected according to aesthetic subunit principles. Slightly greater than half of the subcutaneous fat in the cheeks (57%) is above the SMAS, whereas slightly less than half (43%) is below the SMAS. The fat-laden cheek aesthetic subunits were found to have secondary supporting retaining ligaments located within their borders that provided poor support and primary supporting retaining ligaments along their borders, which provided strong support. These anatomic arrangements, along with the fact that the anterior and middle cheek subunits serve as lining and cover for the hollow intraoral cavity, account for the characteristic and reproducible saggy appearance of the midface and cheeks when subjected to the forces of gravity, motion, time, and the elements.