Superficial Musculoaponeurotic System and Temporoparietal Fascia
The superficial facial fascia, which is an extension of the superficial cervical fascia in the neck, invests the facial mimetic muscles to create the SMAS (Fig 9-1A, B). The SMAS distributes facial muscle contractions, facilitating facial expression. These muscle actions are transmitted to the skin by ligamentous attachments located between the SMAS and the dermis. The SMAS is also connected to the underlying bone by a network of fibrous septa and ligaments. Thus, facial support is transmitted from the deep fixed structures of the face to the overlying dermis. There are 2 major components of this system:
the osteocutaneous ligaments (orbitomalar, zygomatic, and mandibular), which are thick fibrous attachments that originate from the bony periosteum
the fascial cutaneous ligaments (parotidocutaneous and masseteric), which are formed by a condensation of superficial and deep facial fasciae
Figure 9-1 Superficial musculoaponeurotic system (SMAS). A, Illustration shows the SMAS; note that the facial nerve branches inferior to the zygomatic arch are deep to the SMAS. B, The SMAS exposed during a face-lift procedure. The horizontal surgical markings indicate the border of the zygomatic arch, and the oblique lines mark the area of planned excision of the SMAS during the procedure. C, Coronal section of the face. The temporal branch of the facial nerve is found within the superficial portion of the temporoparietal fascia (extension of the SMAS).
(Illustrations by Christine Gralapp. Clinical photo courtesy of Jill Foster, MD.)
As these ligaments become attenuated in conjunction with facial dermal elastosis, facial aging becomes apparent. Dissection and repositioning of the SMAS have important implications for facial cosmetic surgery.
As the SMAS continues superiorly over the zygomatic arch, it becomes continuous with the temporoparietal fascia (also called the superficial temporal fascia). More superiorly, the SMAS becomes continuous with the galea aponeurotica. Beneath the loose areolar tissue and the temporoparietal fascia, the deep temporal fascia of the temporal muscle splits and envelops the temporal fat pad, creating deep and superficial layers of the deep temporal fascia (Fig 9-1C).
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.