Relations of the superficial musculoaponeurotic system to the orbit and characterization of the orbitomalar ligament.

Abstract

The orbital and eyelid relationships of the superficial musculoaponeurotic system (SMAS) were studied in human cadavers. Using gross and microscopic techniques, the SMAS was found to be intimately related to the eyelids and orbicularis oculi muscle, and to have distinct orbital bony attachments. Sub-SMAS fat in the malar region was found to be continuous with the submuscular fat in the eyebrow region. The malar sub-SMAS fat continued superiorly into the lower eyelid above the inferior orbital rim, as a postorbicularis layer. A bony attachment emanating from the inferior orbital rim, the orbitomalar ligament, traveled through the orbicularis oculi muscle in a lamellar fashion prior to inserting into the dermis. The cutaneous insertion of this attachment corresponds to the malar and nasojugal skin folds. With aging, relaxation of the orbitomalar ligament allows inferior migration of orbital fat, in addition to the anterior migration that occurs through an attenuated orbital septum. These findings have implications not only in cosmetic surgery but also in the understanding of facial soft tissue changes that occur with aging.