Facial Retaining Ligaments - and SMAS (Superficial Musculoaponeurotic System)

Hello, this is Dr. Han Kyunam from 345 Plastic Surgery.

Today, let's learn about the retaining ligaments of the face.

Retaining ligaments are structures that help maintain the shape of the face.

Typically, ligaments are strong fibrous tissues that connect bones to other bones, primarily located in joints. They have a structure similar to tendons, which are also fibrous tissues but connect muscles to bones.

Similarly, retaining ligaments are also fibrous connections, but they differ in that they attach to the skin.

In the face, retaining ligaments vary from very firm ones that connect the bone directly to the skin to relatively weaker ones that connect the fascia to the skin.

The following true ligaments are the strongest.

Because they run vertically from deep to superficial layers, they act like partitions that divide the face into different sections.

As shown in this illustration, the facial fat layers are divided by retaining ligaments.

The separated fat layers are named as distinct fat compartments.

(Of course, even in areas without retaining ligaments, fat can still be divided into compartments. This means that fat compartments are not solely defined by retaining ligaments.)

Within these divided spaces, areas that stretch more or less are created due to facial muscle movements, leading to the formation of wrinkles over time.

Although retaining ligaments are present in everyone, they are less noticeable when a person is younger.

This is because, in youth, the surrounding tissues apart from the retaining ligaments are still elastic and have not been stretched.

As aging progresses, tissue elasticity decreases, and repeated movements combined with the effects of gravity cause the skin to sag. As a result, the areas around the retaining ligaments that stretch less appear more indented.

In middle-aged women, hollowness under the cheekbones or more prominent jowls are due to the relatively less sagging, attached, and indented areas.

These indented areas correspond to the locations of retaining ligaments.

The areas that typically sag are those known as jowls (or "bulldog" cheeks) and the area above the nasolabial folds.

However, not everyone has the same skin or bone structure.
(And, of course, the extent of care taken also makes a difference, right? 😊)

Some individuals may experience aging that appears less severe, resembling a subtle loss of volume rather than significant sagging.

When the indentation in the retaining ligament area is bothersome, it can sometimes be corrected by adding volume through fat grafting or fillers.

However, because the retaining ligament "firmly" holds the area in place, it often doesn’t lift easily.

In such cases, the branches of the retaining ligament beneath the skin need to be severed.

This procedure, called subcision, is often performed using an 18G needle without incisions. However, it can easily cause bruising, and even then, the area may not smooth out completely.

When it comes to fillers, each doctor has their own technique. Personally, I use a relatively soft filler injected superficially to correct the issue.

Tear troughs also have their own retaining ligament, and due to the complex anatomical structure around the eyes and the frequent movement in this area, administering fillers can be particularly challenging.

Beyond addressing these sunken areas, retaining ligaments are also significant because they can hinder the transmission of lifting forces.

While they are helpful in resisting the downward pull of gravity, they can prevent upward force transmission unless severed during lifting procedures.

To be more precise, pulling at the retaining ligament areas moves the surrounding tissues collectively (which might sound beneficial). However, such strong upward fixation is not sustainable without proper dissection and soft tissue repositioning, leading to ineffective results.

Therefore, in typical incision-based lifting procedures, severing the retaining ligaments is essential. Since the SMAS (Superficial Musculoaponeurotic System) layer is lifted, the ligaments are cut below the SMAS layer.

In some cases, ligaments may need to be severed twice — once in the subcutaneous layer and again below the SMAS layer, depending on the need.

The reason for lifting the SMAS layer is that it is more robust, and both the deep and superficial fat layers, which are the targets for repositioning, are located above and below this layer.

If only the skin is pulled, especially in individuals with thin and inelastic skin (common among Westerners), the skin quickly stretches back, diminishing the effect. Hence, the SMAS layer must be utilized.

In individuals with firmer tissue, such as Asians or those of African descent, simply excising and pulling the skin can yield effective lifting results due to reduced skin laxity.

However, this can also increase the likelihood of hypertrophic scarring, wide scars, pixie ear deformities, or hair loss, as the tension is borne directly by the skin.

The SMAS (Superficial Musculoaponeurotic System) layer is connected both above and below to the superficial temporal fascia (STF, also known as temporo-parietal fascia) and the platysma muscle. For this reason, they are often lifted together during a lifting procedure.

However, the STF is not typically dissected because the facial nerve passes beneath it, and this area is not usually prone to sagging.

I started talking about retaining ligaments, but ended up discussing the SMAS (Superficial Musculoaponeurotic System)—that was a bit too much information!

There was a lot to cover, but here's one more important point!

Around the retaining ligaments, which are the most rigid, tissues are tightly gathered, and nerves and blood vessels are located nearby. Therefore, careful dissection is required in these areas.

Once there is bleeding, it can be controlled with hemostasis; however, when it comes to the damaging of the nerves, recovery is irreversible.

Surgery requires caution from start to finish, but especially when mistakes can't be corrected, extra attention is necessary.

Wishing you a successful surgery!