The SMAS, short for the superficial musculoaponeurotic system, is a sheet of muscle and fibrous tissue that lies just beneath the fat under the skin of the face, and it is the most important word in facelift surgery. Every modern lift is defined by what it does with this layer: work above it and you are tightening skin, work on it and you are tightening the sheet, work beneath it and you are moving the structure of the face itself. This page is a plain-language anatomy primer built on the published record, defining the SMAS, the sub-SMAS plane, the retaining ligaments, and the origin of the deep plane technique, so that the words you will hear in consultations stop being noise and start being checkable.
What is the SMAS in plain language?
The SMAS is a continuous layer of muscle and thin, tendon-like fibrous tissue that sits under the skin and fat of the face, defined in the surgical literature by Mitz and Peyronie in 1976. Their paper in Plastic and Reconstructive Surgery, on the superficial musculo-aponeurotic system in the parotid and cheek area, gave the layer its name and its map, and facelift surgery has been organized around it ever since.
Picture the face in layers. On top is skin. Under the skin is a layer of fat. Under the fat is the SMAS, a sheet that wraps the face like a soft internal mask and runs down past the jaw, where it becomes continuous with the platysma, the thin sheet of neck muscle. The muscles of expression work through this system: when you smile, muscle pulls on the SMAS and the SMAS moves the skin. That is why the layer matters so much for a natural result. Move the SMAS and the face above it moves as a face. Pull only on skin and you get the look of pulled skin.
What does sub-SMAS mean?
Sub-SMAS means beneath the SMAS: the surgeon develops the working plane under the muscular sheet rather than above it, so skin, fat, and SMAS travel together as one connected unit. A plane, in surgical language, is simply the level at which tissue is separated so that something can be moved. In a facelift there are three broad choices. Above the SMAS is a skin lift, the oldest approach, which tightens the cover and nothing else. At the SMAS is the family of SMAS lifts, which tighten, fold, or trim the sheet while working on it from above. Beneath the SMAS is the deep plane.
The deep plane facelift releases the deep structure beneath the SMAS and repositions it as one unit, so the skin is not the thing carrying tension. That single sentence is the whole logic of the technique, and it is why the results are described as natural and longer lasting. How I perform the operation, step by step, lives on the procedure page; how the deep plane compares with a SMAS lift, citation by citation, lives on deep plane vs SMAS. This page stays with the anatomy.
What are the retaining ligaments and why are they released?
Retaining ligaments are fibrous anchors that run from the bone of the face up toward the skin, holding the soft tissue at fixed points, and the deep layer cannot truly move until they are released. The classic description belongs to Furnas, whose paper on the retaining ligaments of the cheek in 1989 named the zygomatic ligaments, which anchor tissue over the cheekbone, and the mandibular ligament, which anchors it near the front of the jaw. Later anatomical studies added the masseteric ligaments along the front edge of the chewing muscle. Different authors draw the map with slightly different labels, but the principle is constant: the face is tethered to its skeleton at a handful of fixed points.
Those anchors are the reason release matters. Pulling on a sheet that is still tied down does not move the sheet; it creates tension between the pull and the anchor, and tension is exactly what a natural result cannot carry. In the published deep plane technique, the ligaments are released so that the composite flap, skin and SMAS together, can be repositioned and can settle where it is placed rather than where it is pulled. Which ligaments a given surgeon releases, and how far the release is carried, is a technique question, and it is one you are allowed to ask directly.
Who described the deep plane facelift?
The deep plane facelift was described by Sam T. Hamra in 1990, in a paper in Plastic and Reconstructive Surgery titled The deep-plane rhytidectomy. Hamra’s argument was the one this page has been building: instead of tightening the SMAS from above, enter the plane beneath it, release what holds it, and reposition the structure as one unit so the skin is under no tension.
One point deserves to be stated exactly, because it gets blurred online. Bruce F. Connell did not originate the deep plane. Connell, of Santa Ana, California, was a master of face and neck lift surgery and the mentor with whom I did my fellowship training, in 1983 to 1984 and again in 1986. Hamra described the deep plane; Connell taught a generation of surgeons, me among them, the discipline of facial anatomy and the craft of the face and neck lift. Two different surgeons, two different contributions, and a practice that blurs them on its website is telling you something about its precision. My own record, fellowship included, is documented with sources on the Dr. Quiroz page.
Why does moving structure beat tightening skin?
Because skin is a cover and the SMAS is structure: skin stretches and surface tension fades, while a deep layer that has been released and repositioned can hold its new position. This is the anatomical reason behind the longevity difference reported in the literature, where deep plane results are commonly described as holding about ten to twelve years and surface or SMAS lifts about five to ten. Those year ranges are orientation rather than a promise. A systematic review pooling thousands of patients across many studies found that direct, head-to-head comparisons of the two techniques remain few and their outcome measures rarely line up, so no honest surgeon can hand you an exact number. It is also the reason the deep plane reads as natural: a face moved at the structural level is still a face, with its expression system intact, rather than a cover stretched over an unmoved frame. Individual results vary.
What this page will not do is tell you which operation your face needs, because anatomy is general and faces are not. The working comparison between the two structural approaches is on deep plane vs SMAS, and if what you are actually weighing is a smaller operation, mini facelift vs deep plane covers that decision. Both pages exist to answer the which-lift question this primer deliberately leaves open.
How do you ask a surgeon which layer their lift moves?
Ask two questions in plain words: at what plane do you dissect, and what do you release? A surgeon who works beneath the SMAS will answer in anatomy, naming the plane and the ligaments without hesitation, because the answer is simply a description of what happens in the operating room. A vague answer to an anatomical question is a finding, the same way a hesitation over a license number is a finding when you verify a surgeon’s credentials.
Brand names will not do this work for you. The market is full of named lifts, and the name is chosen by marketing while the plane is chosen by the surgeon’s training. The two questions above cut through every label, and a fuller set, covering credentials, facility, anesthesia, and revision policy, is in the questions to ask a facelift surgeon. After 37 years and more than 3,000 facelifts, I can tell you that the patients who ask them are the easiest to talk to, because the conversation starts where it should: at the layer. If you want that conversation about your own face, the consultation starts remotely, with photographs. Call or text +1 (619) 738-2144.