What are the five layers of facial aging?

By Dr. Young Jun Kim, Medical Director, Violacell Plastic Surgery · Board-certified plastic surgeon (Korea)

The face ages in five layers: the skin, the fat just beneath it (subcutaneous fat), the muscle layer with its thin supporting sheet (the SMAS), the deeper fat that lies against the bone, and the bone itself. Each layer changes in its own way and at its own pace, so two faces that look similarly tired in the mirror can have quite different causes underneath. That is why Dr. Kim first works out which layer has actually changed, and only then chooses a treatment that reaches that layer.

Why think in layers at all?

The mirror shows the result, not the cause. A heavy jawline, for example, can come from loosened support tissue, from fuller fat along the jaw, from a large chewing muscle or salivary gland, or from bone that gives the soft tissue less support than before. These look alike from the outside, but each one calls for a different tool, and some call for no device at all.

Dr. Kim has written about this directly. In a post on lifting and the layers of the face, he describes the face as five layers that all age, and writes that lifting should start by looking at every layer to find the cause, and then responding to that cause.

Layer 1: the skin

The skin has a thin outer layer (the epidermis) and a thicker inner layer (the dermis). The dermis holds most of the skin's collagen and elastic fibers, which give it firmness and spring.

What changes: the body makes less collagen with age and breaks more of it down. The dermis thins and loses elasticity.
How it looks: fine lines, crepey or dull skin, enlarged pores, and skin that does not spring back as quickly.
What can reach it: radiofrequency such as Thermage heats a broad zone of the dermis; a skin booster such as Re2O is injected into the skin to support its quality; Ulthera's shallower 3.0 mm and 1.5 mm depths also act in the dermis.
What it cannot do: treating the skin does not move tissue that has already descended, and it does not remove excess skin.

In his answers to patients, Dr. Kim notes that when fine wrinkles and skin elasticity are the main goal, radiofrequency devices are better suited than focused ultrasound, which works deeper.

Layer 2: the fat just under the skin

The fat beneath the skin is not one even sheet. It is divided into separate pockets, or compartments, by thin fibrous walls. These compartments do not age in the same way.

What changes: some compartments shrink, for example at the temples and around the eyes. Others become heavier or slide down, for example beside the mouth, along the jaw and under the chin.
How it looks: hollows sitting next to fullness, such as a hollow temple above a heavy jowl. This mix is one reason a face can look both thin and saggy at once.
What can reach it: where volume is lost, a collagen stimulator such as Sculptra can rebuild support gradually. Where fat is fuller, Ulthera's energy can be planned at the fat level as well as deeper. Where a localized pocket of fat is the main problem and the skin is firm, liposuction removes it surgically.
What to watch: reducing fat in a face that is already lean can make it look hollower, so fat is assessed area by area before energy is placed.

Layer 3: the muscle and the SMAS

Under the fat lie the muscles of facial expression, wrapped in and connected by a thin, firm sheet called the SMAS (superficial musculoaponeurotic system). The SMAS is the layer a surgical facelift repositions, and it is the main target of Ulthera's 4.5 mm depth where the tissue is thick enough.

What changes: the SMAS loosens and the tissue on top of it slowly descends. Muscle pull also matters. Dr. Kim writes that some muscles pull the face downward, such as the frown muscle between the brows, the muscle that pulls the mouth corners down, and the thin neck muscle (platysma), while the forehead muscle pulls upward. Relaxing the downward-pulling muscles can support a lift.
How it looks: a softer jawline, early jowls, mouth corners that turn down, and bands in the neck.
What can reach it: Ulthera for early laxity of the SMAS; muscle-relaxing injections in selected muscles; and, when tissue has clearly descended, surgery such as a mini facelift or facelift.

Layer 4: the deep fat

Beneath the muscle layer, close to the bone, sit deeper fat pads. In the midface they support the cheek from below, much like a cushion under a cover.

What changes: deep fat in the midface tends to lose volume with age. The cheek then loses support from underneath, and the tissue above it settles lower.
How it looks: a flatter cheek, a deeper groove under the eye, and a deeper fold beside the nose and mouth, even when the skin itself is in fair condition.
What can reach it: volume support such as Sculptra, which in some areas, such as the temples and over the cheekbone, is placed deep and close to the bone. A facelift can reposition descended tissue but does not replace lost volume.

Dr. Kim has written that the depth of the SMAS, the position of fat and the shape of the deep cheek fat differ from person to person, which is one reason he values the deeper, sharper ultrasound image of Ultherapy PRIME when planning.

Layer 5: the bone

The facial skeleton is the frame that everything else hangs on, and it changes too. With age the eye sockets tend to widen, and parts of the midface and jaw lose some height and projection. The soft tissue then has less to rest on.

How it looks: the face can look longer and the soft tissue looser, even without much change in the skin.
What can reach it: no device or injection rebuilds bone. Volume treatment can partly make up for lost support.
Why it still matters: bone contours shape every plan. On Ulthera's image, bone shows as a bright line, and energy is not placed on bone. Dr. Kim's 2026 lecture to clinicians on collagen booster injection was built around each person's facial skeleton as well as the tissue layers (report).

What holds the layers together

Strong fibrous bands called retaining ligaments run from the bone up through the layers to the skin. They act as anchor points. With age, tissue between the anchors sags while the anchors stay put, which is what outlines a jowl or a fold.

The five layers at a glance

Layer	Typical change	Treatments that reach it	What they cannot do
Skin	Thinning, fine lines, less elasticity	Thermage, skin booster such as Re2O, Ulthera's shallow depths	Move descended tissue or remove skin
Subcutaneous fat	Some pockets shrink, others get heavier	Sculptra for lost volume; planned Ulthera energy; liposuction (surgery)	Fix fat and laxity with one tool
Muscle and SMAS	Loosening, downward pull	Ulthera 4.5 mm, muscle-relaxing injections, facelift (surgery)	Devices cannot reposition clearly descended tissue
Deep fat	Volume loss in the midface	Volume support such as Sculptra	A lift alone does not restore volume
Bone	Gradual loss of projection	Partial compensation with volume	No treatment rebuilds bone

How the layers are examined

At consultation, the face is looked at from the front and side, at rest and while talking and smiling. Dr. Kim then examines by touch (palpation): how thick the tissue is in each area, where fat is soft and abundant, where it is thin, where bone edges lie and how the tissue moves. Your history fills in the rest: weight changes, previous fillers, threads, energy treatments or surgery. For Ulthera, the real-time ultrasound image adds a view of the skin, fat, SMAS and bone in each spot before energy is delivered.

Why it matters who plans it

Reading the layers is the step that decides everything after it. Dr. Kim trained in plastic surgery at Chonnam National University, where he later served as a clinical professor, so he learned the SMAS, the ligaments and the fat compartments by seeing them directly in surgery. When the clinic opened he said that few doctors who perform aesthetic treatments look at both the inside and the outside of the tissue, and that procedures and surgery should be weighed together for the patient (interview, 2024). For Ulthera he plans from the ultrasound image and palpation together. Why Dr. Kim for Ulthera, Sculptra and Thermage

Limits and honest expectations

Most faces show change in more than one layer, and no single treatment covers all five. Non-surgical results are gradual and modest, vary between people, and fade as aging continues; each treatment page lists its own risks. When tissue has clearly descended or there is excess skin, surgery is usually the better answer. Dr. Kim will say so, although his practice at Violacell is non-surgical and he does not perform surgery there.

Common questions

Which layer of the face ages first?

It varies. Changes in the skin and in some fat compartments often show earlier, while bone changes are slower. Genetics, sun exposure, smoking and weight changes all shift the pattern, which is why each face is examined layer by layer.

Can one treatment address all five layers?

No. Thermage and skin boosters act mainly on the skin, Sculptra on volume and support, and Ulthera on the deeper supporting layer and the dermis. No treatment rebuilds bone, and only surgery removes excess skin.

Why can my face look hollow and saggy at the same time?

Fat compartments age differently. Some shrink, for example at the temples, while others become heavier or slide down along the jaw. The result is hollows next to fullness, which usually needs a different tool for each area.

Does Ulthera reach the deep fat or the bone?

No. Its deepest standard depth, 4.5 mm, is aimed at the SMAS where the tissue is thick enough, and energy is not placed on bone. Lost deep volume is addressed with volume support rather than energy.