The term "laughing muscle" is not precise, as laughter involves many muscles. However, the zygomaticus major is often considered the primary muscle responsible for smiling, a key component of laughter.
The Zygomaticus Major and Laughter
The zygomaticus major muscle is a key player in creating a smile. As stated in multiple sources including Amboy Orthodontics (https://amboyortho.com/what-muscle-is-used-in-smiling/) and other articles, this muscle works in conjunction with up to 43 other facial muscles to produce a variety of smiles and expressions associated with laughter. A full, hearty laugh engages numerous muscles throughout the face and even the core.
Other Muscles Involved in Laughter
While the zygomaticus major is prominent in smiling, laughter is a more complex activity involving multiple muscle groups:
- Facial Muscles: Numerous muscles around the eyes, mouth, and cheeks contribute to the various expressions associated with laughter.
- Trunk Muscles: Research, such as the study "Laughing: a demanding exercise for trunk muscles" (https://pubmed.ncbi.nlm.nih.gov/24246140/), indicates that laughter significantly engages the core muscles. This highlights the physical exertion involved in laughter.
The Risorius Muscle
Merriam-Webster (https://www.merriam-webster.com/dictionary/laughing+muscle) defines the "laughing muscle" as the risorius. The risorius is a muscle involved in smiling and contributes to laughter. However, its role is less prominent than the zygomaticus major.
In summary, while there isn't a single "laughing muscle," the zygomaticus major plays a critical role in the smiling aspect of laughter, and many other facial and trunk muscles participate in the full expression. The risorius muscle also contributes to the overall expression.
