What is SMAS?
3 December 2019 onur
In this post, I’m going to talk about a medical terminology that everyone who searches online information about facial rejuvenation surgeries eventually comes across and which confuses prospective patients.
In short: SMAS
In its original name: Superficial MusculoAponeurotic System
In Turkish: Superficial muscle and connective tissue layer
During my plastic surgery fellowship at Cleveland Clinic, the subject of my thesis was to investigate the deep plane surgical anatomy of the face and the relationship of the SMAS layer with the vascular facial nerve structures. The results of this research were rewarded with the best cosmetic paper of the year award at the American Society of Plastic Surgery congress in New Orleans in 2012 and were published in the Journal of Plastic and Reconstructive Surgery, the most prestigious scientific publication of our community, the next year.
I don’t intend to take you to an anatomy laboratory, but to make this important anatomical structure, which I know very well and which is a part of my daily surgical practice, more understandable.
The anatomy of the face and neck consists of layers, like a cake.
The top layer is the skin. There are two different layers of adipose tissue just under the skin. Below that is our famous SMAS layer. Let’s call everything under the SMAS layer “deep tissues” for ease of description.
To understand the importance of the SMAS layer in terms of facial rejuvenation, it is necessary to know some of its features.
- This layer extends uninterruptedly throughout almost the entire head and neck region from the scalp to the neck.
- The bulk of the tissue that loosens and sags with gravity is in this layer.
- It contains superficial curtain-shaped muscles which play a key role in the relaxation and sagging of the eyelids and neck.
- The nerves that pose a danger and move the facial muscles are located two layers below the SMAS layer.
- A facial rejuvenation surgeon who has mastered the surgical anatomy can safely remove this SMAS layer along with the overlying skin without damaging the underlying nerves.
- Eliminating the laxity in this layer is the basis of modern facial rejuvenation techniques.
- There are 3 main approaches that could be employed to get rid of laxity in this layer: partial resection and suturing (SMASectomy), folding inwards and suturing without resection (SMASplication), dissecting the SMAS layer from the deep tissues, repositioning and fixing it (SMASlift). Each approach has its own modifications and technical nuances.
- The anatomy of the SMAS layer may differ significantly one person to the other and even between the right and left sides of the same person’s face.
- Even if the skin is lifted, it loosens again over months and years due to its flexible structure and cannot maintain the tension secured during surgery. Therefore, surgeries based on the principle of lifting the skin create an undesirably “tense” appearance on the skin in the early period, and its effects are relatively short-lived. Unlike skin, SMAS is a “not too flexible” layer. Therefore, the SMAS is not lifted and stretched, it is just repositioned. It can maintain its new position for many years when the appropriate surgical technique is used.
- Surgery of the SMAS layer is highly specialized and requires additional training and experience.
If you’re wondering how approaches to the SMAS layer change/improve facial rejuvenation surgeries, I recommend you take a look at my post on “deep plane facelift”.
Take good care…
… of yourself and your beauty.