Why Nasolabial Folds and Eye Wrinkles Develop: An Anatomical Assessment of Facial Aging

This is the full text of my column in the July 2025 issue of D&PS.

Facial skin aging begins as early as the twenties, while fat and muscle changes begin around the mid-thirties. Tissues around the scalp and ears contain little subcutaneous fat and have a thick, tough SMAS that resists stretching, with firm internal connections. In contrast, the cheeks around the nose and mouth and the tissues along the jawline have a thinner SMAS, more fat, and looser internal attachments, making them more prone to descent with age.

Why do wrinkles appear around the eyes first?

Skin around the eyes is only one-fifth to one-seventh as thick as skin elsewhere on the face, so it is the first area to develop wrinkles. Just as people with naturally thin, delicate skin develop lines early, this region shows collagen loss, reduced elasticity, and increasing wrinkles at a relatively young age.

Our eyes move constantly in every direction. Abundant fat surrounds them to absorb shocks within the bony orbit. When the surrounding skin and muscles lose elasticity, the tissues commonly bulge forward. Fat above and below the eye is often connected, so gravity can redistribute upper orbital fat downward. The resulting combination of upper-eyelid hollowing and bulging lower-eyelid fat is a familiar sign of aging around the eyes.

Alongside these skin and fat changes, ligaments anchoring the skin to bone form an oval around the orbit. In contrast with protruding orbital fat, the tear trough becomes visible as a line tethered to the underlying bone.

Figure 1. Sagittal section showing important midfacial anatomy. Release of the orbitomalar and zygomatic cutaneous ligaments is important for mobilizing the midface. Source: https://plasticsurgerykey.com/midface-lift.

What causes under-eye hollows and nasolabial folds?

Under-eye aging is often reduced to “bulging fat,” leading some people to assume that removing it is all that is needed. In 2005, however, R. A. Goldberg and colleagues evaluated several components: tear-trough depression, orbital fat prolapse, reduced skin elasticity, eyelid edema, orbicularis prominence, and malar mounds. In “What Causes Eyelid Bags? Analysis of 114 Consecutive Patients,” the authors also assigned numerical scores to these features.

The retaining ligaments around the eye, including the orbicularis retaining, tear-trough, and zygomatic cutaneous ligaments, play important roles in lower-eyelid aging. The visible protrusions and hollows of the under-eye area and midface are often described as mounds and grooves. Mounds include lower-lid bulges, malar mounds, and malar fat pads. Grooves include the tear trough, comprising the nasojugal and palpebromalar grooves, the midcheek groove, and the nasolabial fold. These contours emerge from the interplay of retinacula cutis, retaining ligaments, and muscles of facial expression that influence superficial fat migration and tension. Some people are most bothered by a hollow tear trough; others by the bulging, descended malar fat pad between the midcheek groove and nasolabial fold.

With age, nasolabial folds deepen and a parallel midcheek groove may also become apparent. When marionette lines and jowls develop and jawline definition is lost, the boundary between face and neck becomes unclear. Children often begin drawing a face with its outline; a clearly defined facial border does, in fact, give a sharper, more youthful impression.

Four midface muscles involved in smiling lift the nasolabial region, three pull the mouth corners and jawline downward, and one elevates the chin. With age, the mouth corners and jawline tend to descend while the chin becomes more prominent. Deep fat pads form the deepest layer of the nasolabial region, with muscles of facial expression running in several directions above them.

The broad space beneath the cheekbone allows muscles to attach at different angles, and superficial fat covers these muscles. The main muscles attaching to the nasolabial fold are the levator labii superioris alaeque nasi, levator labii superioris, and zygomaticus major and minor.

Why do lines and drooping develop around the mouth?

The first type of nasolabial fold reflects local differences in tissue volume, particularly insufficient volume beside the nasal ala. The canine fossa of the maxilla, which supports this region from below, is recessed. Nasolabial fat bulges above the fold, while there is naturally very little superficial fat below it beside the nostril.

The second type results from age-related soft-tissue descent. Upper-lip skin below the fold is relatively firmly attached to the underlying orbicularis oris and stretches less. Skin and tissue above the fold are more loosely attached. With age, superficial nasolabial fat over the anterior cheek thickens and descends over the firmly attached upper-lip skin. Filler placed along such a fold may be unable to move downward and instead shift upward. This can make the region above the fold fuller and the crease more pronounced.

The third type arises as muscles originating at the cheekbone descend toward the mouth corner and run superficially, pulling on skin beneath the lower border of the nasolabial fat. These include the levator labii superioris alaeque nasi, levator labii superioris, and zygomaticus major and minor.

A marionette line is an oblique crease descending from the mouth corner toward the jawline that remains visible at rest, also called a static labiomandibular fold. It usually runs backward along the posterior border of the depressor anguli oris and reflects the combined effects of bone, ligaments, and soft tissues. In White and Black populations, the modiolus (the muscular convergence near the mouth corner) usually lies at or above the corner. In East Asian populations, including Koreans, it commonly lies about 11 mm lateral and 9 mm inferior to it. This helps explain why the mouth corners may appear more downturned at rest in East Asian faces.

Among East Asian individuals as well, a lower modiolus is associated with a greater tendency toward mouth-corner descent and creasing with age. The most superficial modiolus muscle, the depressor anguli oris, and the superficial and deep fibers of the intermediate-depth orbicularis oris occupy different planes. Greater separation between these planes can allow a depression at the mouth corner and an oblique vertical commissural line.

A substantial thickness difference between superficial jowl fat on the cheek and the subcutaneous tissues of the lower lip can deepen the commissural line and cause mouth-corner drooping.

Figure 2. Anatomical relationships of lower facial muscles contributing to jowl and marionette-line formation.

How do jowls develop?

Jowls may develop through inferior migration of the fat compartment itself or loosening of the mandibular septum. Migration of the compartment produces more pronounced submalar hollowing. Jowling involves shortening of the supraplatysmal plane, with relatively little descent beneath the platysma. Skin stretching contributes, but redundant subcutaneous tissue also develops.

Traditionally, the mandibular ligament was thought to form a tight bone-to-skin attachment responsible for jowls and marionette lines, with the anterior jowl border corresponding to the marionette line. A recent paper, “The Surgical Anatomy of the Jowl and the Mandibular Ligament Reassessed,” instead found that maximal jowl fullness lies over the posterior end of the mandibular septum. This is where the mandibular ligament ends and, histologically, where the retinacular fibers are longest. The authors also found that subplatysmal structures do not contribute to jowl volume.

Micro-CT examination of tissues around the jowl showed that muscle attaches to bone, but the connection from muscle to skin consists of dense and loose retinacula cutis rather than a firm ligamentous structure. The authors propose that this allows skin gliding when the mouth opens. The deep third of the mandibular ligament interconnects with the platysma, depressor labii inferioris, and depressor anguli oris and attaches close to bone. Toward the skin, however, it is described as a dense retinacular structure rather than a true osteocutaneous ligament extending from bone to skin.

Skeletal changes occur slowly but affect both soft tissues and overall facial form. A slight increase in anterior facial height, mostly in the lower face, begins in the twenties and thirties; mandibular length continues to increase afterward. Maxillary retrusion in the thirties and forties influences the nasolabial folds. Craniofacial remodeling progresses from the forties and fifties onward, and after the sixties, craniofacial convexity changes substantially across the maxilla and mandible.

(To be continued in the next issue)

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