Why the face sags with age: what changes in each layer, from skin to bone

Wrinkles and skin are not the only reasons a face looks older. The face is built in layers, from the skin down to the bone, and each one changes with age in its own way. The sagging and hollowing people notice are not the fault of a single layer but the combined result of changes in several. This article follows those layers from the outside in: skin, superficial fat, the SMAS and retaining ligaments, deep fat, and bone.

The skin loses elasticity

The skin is the outermost layer, and here collagen in the dermis falls with age (Shuster 1975, PMID 1220811). Heavy sun exposure speeds the loss. With less collagen and fewer elastic fibers, the skin thins and loses its elasticity, so fine lines appear and the texture changes (Calleja-Agius 2007, PMID 17540135).

The loss of elasticity shows up from the twenties. In a study of 300 people aged 20 to 74, skin elasticity was recorded with a suction device. Every value fell steadily with age, and the skin's ability to spring back after stretching fell the most (Luebberding 2014, PMID 23889488).

The superficial fat sags

The skin alone, however, does not explain why the face sags. The fat beneath it is not one mass but a set of compartments, and the SMAS, a fibrous layer wrapping the muscles of expression, splits them into superficial fat above and deep fat below (Rohrich & Pessa 2007, PMID 17519724; Ramanadham & Rohrich 2015, PMID 26441111; Mendelson & Jacobson 2008, PMID 18558234).

The superficial fat sits just under the skin, and with age it slides downward. In a CT study of cadaver heads, those aged 75 to 104 were compared with those aged 54 to 75. The midface compartments had moved lower, thinner at the top and fuller at the bottom (Gierloff 2012, PMID 21915077). Much of the sagging you can see is this descent.

The SMAS, retaining ligaments, and fibrous septa loosen

Fat and skin stay in place because structures beneath them hold them there. One is the SMAS described above, and the other is the retaining ligaments, fibrous bundles that rise from the bone or the deep fascia and anchor the SMAS and the soft tissue above it (Mendelson & Jacobson 2008, PMID 18558234).

The retaining ligaments do not stop at the SMAS. They pass through it, branch into finer strands that divide the fat into compartments, and reach the skin. Those strands are the fibrous septa. Ligaments and septa are one system that supports the soft tissue from bone to skin (Alghoul & Codner 2013, PMID 23855010; Minelli 2024, PMID 37747400).

With age the SMAS loses elasticity, and the ligaments grow thinner and weaker, so they hold less firmly. One report describes the lower lid and the tissue beneath it settling downward as the orbicularis retaining ligament, which supports the lid, loosens (Muzaffar & Mendelson 2002, PMID 12172154).

The deep fat deflates

The deep fat lies beneath the SMAS, on the facial bones, and props the face up from inside. With age it loses volume. When the deep medial cheek fat deflates, the cheek loses its inner support, the fold beside the nose deepens, and the cheek looks sagged.

This is called pseudoptosis, a false sagging: the tissue has not come down but looks lower because the fat beneath it has emptied (Rohrich, Pessa & Ristow 2008, PMID 18520902).

The bone itself shrinks

At the deepest level, the facial bones are slowly resorbed. Certain areas recede in a predictable pattern with age, above all the rim of the eye socket, the upper jaw beside the nose, and the front of the chin (Mendelson & Wong 2012, PMID 22580543). As the bone recedes, the soft tissue above it has less to rest on, and sagging and hollowing stand out more.

Looking at one layer is not enough

In short, facial aging is not a change in one layer but in all of them: skin, fat, the SMAS and its ligaments, and bone. Pulling the skin tight alone does not solve sagging and hollowing, because the cause lies in several layers at once. Those layers have to be treated as a whole.

We explain how to match a skin tightening device to the layer in Ultherapy, Sofwave, or Thermage: which skin tightening treatment is right for you?.

References

1. Shuster S, et al. (1975). The influence of age and sex on skin thickness, skin collagen and density. Br J Dermatol. PMID 1220811 (opens in new window).
2. Calleja-Agius J, et al. (2007). Skin ageing. Menopause Int. PMID 17540135 (opens in new window).
3. Luebberding S, Krueger N, Kerscher M. (2014). Mechanical properties of human skin in vivo: a comparative evaluation in 300 men and women. Skin Res Technol. PMID 23889488 (opens in new window).
4. Rohrich RJ, Pessa JE. (2007). The fat compartments of the face: anatomy and clinical implications for cosmetic surgery. Plast Reconstr Surg. PMID 17519724 (opens in new window).
5. Ramanadham SR, Rohrich RJ. (2015). Newer understanding of specific anatomic targets in the aging face as applied to injectables: superficial and deep facial fat compartments. Plast Reconstr Surg. PMID 26441111 (opens in new window).
6. Gierloff M, et al. (2012). Aging changes of the midfacial fat compartments: a computed tomographic study. Plast Reconstr Surg. PMID 21915077 (opens in new window).
7. Rohrich RJ, Pessa JE, Ristow B. (2008). The youthful cheek and the deep medial fat compartment. Plast Reconstr Surg. PMID 18520902 (opens in new window).
8. Mendelson BC, Jacobson SR. (2008). Surgical anatomy of the midcheek: facial layers, spaces, and the midcheek segments. Clin Plast Surg. PMID 18558234 (opens in new window).
9. Alghoul M, Codner MA. (2013). Retaining ligaments of the face: review of anatomy and clinical applications. Aesthet Surg J. PMID 23855010 (opens in new window).
10. Minelli L, Brown CP, van der Lei B, Mendelson B. (2024). Anatomy of the facial glideplanes, deep plane spaces, and ligaments: implications for surgical and nonsurgical lifting procedures. Plast Reconstr Surg. PMID 37747400 (opens in new window).
11. Muzaffar AR, Mendelson BC, Adams WP. (2002). Surgical anatomy of the ligamentous attachments of the lower lid and lateral canthus. Plast Reconstr Surg. PMID 12172154 (opens in new window).
12. Mendelson B, Wong CH. (2012). Changes in the facial skeleton with aging: implications and clinical applications in facial rejuvenation. Aesthetic Plast Surg. PMID 22580543 (opens in new window).