The appearance of a downturned mouth, sometimes referred to as oral commissure descent, is a common facial concern. This characteristic can unintentionally suggest sadness, tiredness, or a perpetually grumpy demeanor, even when a person feels perfectly content. The downward angle of the mouth corners is not caused by a single factor but is instead a result of a complex interplay between the face’s underlying structure, the condition of the skin, and the activity of the facial muscles.
Anatomy and Structural Changes Causing Downturn
The primary reasons the corners of the mouth begin to angle downward are passive and structural, largely stemming from the natural aging process. Over time, the force of gravity gradually pulls facial tissues downward, compounded by the diminishing capacity of the skin to resist the pull. The skin’s structural proteins, collagen and elastin, decrease in production and quality with age, leading to a loss of firmness and elasticity across the lower face.
A significant contributor is the loss of volume in the subcutaneous fat pads that support the cheeks and the area around the mouth. These fat compartments deflate and shift, removing the foundational support necessary to keep the oral commissures—the points where the upper and lower lips meet—elevated. The resulting lack of support allows the tissue to droop, creating the appearance of vertical creases, known as marionette lines, that extend from the mouth corners toward the chin.
Even the underlying skeletal foundation contributes to this change. Subtle but significant bone resorption occurs in the jawbone (mandible) with age, particularly in the prejowl area. This reduction in bone structure alters the shape of the lower face, further diminishing the scaffolding that supports the soft tissues of the mouth and chin.
The Role of Facial Muscle Activity and Habitual Expressions
In contrast to the passive structural descent, the active downward pull is driven by specific facial muscles. The Depressor Anguli Oris (DAO) muscle is the primary culprit in creating a downturned mouth, as its anatomical function is to pull the corner of the mouth down and slightly outward when expressing sadness or displeasure. This triangular-shaped muscle originates from the lower jawbone and inserts into the angle of the mouth.
For many people, the DAO muscle becomes chronically overactive or hypertonic, meaning it maintains a state of tension even when the face is at rest. This chronic hyperactivity can be a genetic trait, but it is often reinforced by habitual facial expressions. Repeated actions like frowning, scowling, or holding a tense expression can train the DAO to remain contracted, leading to a permanent downward angle of the mouth corners.
This downward pull is often unopposed because the muscles responsible for lifting the mouth corners, such as the Zygomaticus major and minor, may be proportionally weaker. The imbalance between the chronically tight depressor muscles and the relatively weaker elevator muscles exaggerates the appearance of a frown at rest.
Managing the Appearance of a Downturned Mouth
Management strategies often involve a combination of approaches. Non-invasive management can begin with facial awareness, focusing on consciously relaxing the lower face to reduce the habitual tension in the DAO muscle. While facial exercises may offer subtle, long-term benefits, they are generally slower and less predictable than clinical interventions.
For addressing the overactive muscle component, a targeted treatment involves the use of neuromodulators, such as Botulinum Toxin (Botox). When injected directly into the DAO muscle, the neuromodulator temporarily blocks the nerve signals that cause the muscle to contract. This temporary relaxation of the DAO muscle reduces its downward pull, allowing the mouth corners to relax and achieve a subtle, natural-looking lift.
To address the structural component of volume loss and sagging tissue, dermal fillers are commonly used. These injectable gels are strategically placed beneath the oral commissures and in the surrounding areas of volume depletion. The filler restores lost volume, providing structural support to prop up the mouth corners and soften the appearance of marionette lines. For individuals with more severe descent or significant skin laxity, more intensive options like a corner lip lift surgery or a lower facelift may be considered.