The human face conveys a vast range of emotions using facial muscles that attach directly to the skin rather than solely to bone. These muscles of facial expression allow for the subtle shifts that differentiate joy from sadness. A long-standing piece of trivia asks whether it takes more muscular effort to smile or to frown. This question requires a closer look at the specific muscle groups activated by each expression.
The Anatomy of a Smile
A smile is driven by several muscle groups that elevate the corners of the mouth and the cheeks. The Zygomaticus Major muscle is the main driver, originating on the cheekbone and inserting into the skin at the corner of the mouth. When this muscle contracts, it pulls the mouth corners upward and outward, forming the characteristic curve of happiness. This movement alone creates what is often referred to as a “social smile” or a polite expression.
The depth of a smile requires the Orbicularis Oculi. This muscle encircles the eye, and its contraction pulls the cheeks upward, creating the distinctive crinkling at the outer corners of the eyes known as “crow’s feet.” A smile that involves both the Zygomaticus Major and the Orbicularis Oculi is known as a Duchenne smile, and is widely recognized as an indicator of true enjoyment.
Other muscles, like the Risorius, may also assist in pulling the mouth corners laterally for a broader, less genuine smile. The involvement of the eye muscle is particularly significant because its action is largely involuntary, making the Duchenne smile difficult to consciously fake. The overall complexity of a smile depends heavily on its intensity and authenticity.
The Mechanics of Frowning
Frowning relies on a different set of muscles that primarily pull facial features downward and inward. This expression is often associated with concentration, displeasure, or sadness, and it involves a furrowing of the brow. The main muscle responsible for drawing the eyebrows together is the Corrugator Supercilii, located deep beneath the eyebrow. Its contraction creates the vertical wrinkles seen between the eyebrows, which is a hallmark of a classic frown.
Complementing this action is the Procerus muscle, which is located at the bridge of the nose. The Procerus pulls the skin between the eyebrows downward, contributing to the horizontal lines across the top of the nose. Together, the Corrugator Supercilii and Procerus muscles create the appearance of a furrowed brow.
The lower part of a frown is controlled by muscles around the mouth, particularly the Depressor Anguli Oris. This muscle originates near the chin and pulls the corners of the mouth down. A full frown combines the downward movement of the mouth with the inward and downward pull of the brow muscles, engaging a coordinated group of depressor and constrictor muscles.
Direct Comparison and Dispelling the Myth
The common belief that “it takes more muscles to frown than to smile” is a widespread piece of folklore, often citing numbers like 43 muscles for a frown and only 17 for a smile. Anatomical analysis reveals that this simple numerical comparison is inaccurate, as the actual count depends entirely on the definition and intensity of the expression. The number of muscles involved is not a fixed quantity for either action.
For a minimal expression, a simple frown—only lowering the corners of the mouth—can be achieved using as few as four to six muscles. Similarly, a slight, polite smile that only raises the corners of the mouth might use just four to ten muscles. In these basic, low-effort movements, smiling can technically require fewer muscles than a deep, full-face frown.
However, when comparing a full, genuine Duchenne smile to a simple, mouth-only frown, the smile often involves a greater number of muscle units. A broad, toothy grin that engages the mouth, cheeks, and eyes can recruit over a dozen muscles. The complexity of the expression, not the emotion itself, dictates the final muscle count. The myth gained traction by comparing a simple, posed smile to a complex, full-face expression of distress, misrepresenting the full range of both movements.