The primary muscle responsible for smiling is the zygomaticus major. This muscle is often called the "smiling muscle."
Understanding the Zygomaticus Major
The zygomaticus major is located on each side of the face. It originates from the zygomatic bone (cheekbone) and inserts into the corner of the mouth. When this muscle contracts, it pulls the corners of the mouth upward and outward, creating a smile.
Several other facial muscles contribute to the complexity of a smile, including the zygomaticus minor and the risorius. However, the zygomaticus major plays the most significant role in producing the characteristic upward movement of the mouth corners. The number of muscles involved in a smile can vary, depending on the intensity and type of smile. Some sources mention as few as 13 muscles being used, while others state that up to 53 muscles may contract during a smile. This variance is likely due to the involvement of muscles beyond the core smile-producing ones, including those involved in expression and eye movement.
- Zygomaticus Major: The main muscle responsible for smiling.
- Zygomaticus Minor: Assists the zygomaticus major in smiling.
- Risorius: Contributes to smiling by pulling the corners of the mouth laterally (sideways).
- Orbicularis Oculi: The muscle around the eyes, often involved in smiling, causing "crow's feet".
It's important to note that a genuine, Duchenne smile, involves not only the zygomaticus major but also the orbicularis oculi, which contracts to raise the cheeks and cause wrinkles around the eyes. A genuine smile is considered more expressive and less controllable than a non-genuine smile.
Other Muscles Involved
While the zygomaticus major is the key player, other facial muscles contribute to the overall expression and appearance of a smile, creating a more nuanced and complex movement.
