The notion that frowning requires more muscles than smiling is a frequently repeated claim. This popular claim often suggests a simple smile uses as few as 17 muscles, while a deep frown might recruit more than 40. This wide disparity is often used to encourage optimism, implying that positivity is the path of least physical resistance. A closer look at the complex anatomy of the face, however, reveals that the truth is far more nuanced than a simple muscle count. The actual number of muscles involved depends entirely on the intensity and type of expression being performed.
The Anatomy of Facial Movement
The human face contains approximately 43 individual muscles, all controlled by the seventh cranial nerve, known as the facial nerve. These muscles are unlike skeletal muscles elsewhere in the body because they insert directly into the skin or fascia, allowing for the subtle movements that create expression. They can be broadly categorized into groups based on their action, such as elevators that pull features up and depressors that pull them down.
The primary muscles associated with drawing the mouth upward into a smile are the Zygomaticus major and minor. These muscles originate from the cheekbone and insert near the corners of the mouth and upper lip, pulling them superiorly and laterally. The Risorius muscle assists by pulling the corner of the mouth directly outward, which helps to create a social or polite smile.
Muscles involved in creating a frown generally work to pull facial features downward and inward. The Depressor anguli oris actively pulls the corners of the mouth down. The Corrugator supercilii and the Procerus muscles are responsible for the brow furrow, pulling the eyebrows together and creating vertical wrinkles above the nose. A full expression of distress can also engage the Platysma, a broad sheet of muscle in the neck that helps pull the lower lip and mouth corners down.
Comparing the Actions: Muscle Count vs. Effort
Facial expressions exist on a spectrum, not as fixed states. When trying to count how many muscles are used, researchers must decide where a simple mouth movement ends and a full emotional expression begins. The popular figures, such as 43 to frown versus 17 to smile, are often based on broad estimates that lack scientific consensus and vary widely between sources.
A more specific analysis comparing a complex, genuine smile to a full frown suggests the numbers are much closer. For example, some anatomical reviews have proposed that a genuine smile, known as a Duchenne smile, may involve 12 muscles, while a full frown might use 11. A Duchenne smile is characterized not just by the mouth corners being lifted by the Zygomaticus major, but also by the contraction of the Orbicularis oculi muscle around the eyes, creating the characteristic ‘crow’s feet’.
A simple social smile, which is less genuine and involves only the mouth, uses fewer muscles and does not activate the Orbicularis oculi. A minimal frown, consisting only of the mouth corners turning down, may use only the Depressor anguli oris muscles. The complexity of the expression, rather than the emotion itself, determines the total muscle recruitment. A beaming, full-face smile can engage a large number of synergistic muscles, potentially rivaling or exceeding the count for a mild scowl.
The Source of the Smile vs. Frown Myth
The idea that frowning is a greater physical chore stems partly from the subjective feeling of effort and the nature of the expressions themselves. Frowning often involves the use of antagonistic muscles, meaning opposing muscle groups are activated simultaneously. For instance, the muscles that pull the brow down and together are often countered by the muscles that try to keep the forehead smooth, creating tension.
This simultaneous action of opposing muscles can increase the perceived physical effort required to hold a deep frown. Conversely, smiling movements, which are generally upward and outward, often involve fewer antagonistic conflicts. The muscles used for smiling, such as the Zygomaticus major, are used far more frequently in positive social interactions. The frequent use of smiling muscles may lead to greater endurance, making the movement feel easier and more natural than the less-practiced muscles of a deep frown. The myth also has a psychological component, as it serves as a simple and memorable motivational statement.