The muscles of the face are able to perform many detailed movements, and the zygomaticus major is one of the most important muscles responsible for the creation of a smile. This facial muscle is also known as the musculus zygomaticus major or the greater zygomatic muscle, according to a study in the International Journal of Anatomy and Research (IJAR).
How This Muscle Helps You Smile
On your skull, this muscle begins at the zygomatic bone, which is more commonly known as the cheek bone and runs to the corner of the lips, notes the IJAR study. When the greater zygomatic muscle is contracted, or pulled tighter, it draws the corners of the mouth upward and outward. You can visualize this movement as a string that simultaneously pulls both sides of the lips toward your ears, resulting in a smile. When this muscle relaxes, or loosens, your lips go back down to their normal resting position.
The facial nerve transmits messages between your brain and your muscles to prompt the movement of the zygomaticus, as well as all muscles of facial expression, as explained by the Yale School of Medicine. Besides controlling facial expressions, this nerve has many unique functions, including delivering the sense of taste in the first two-thirds of your tongue and the sensation in parts of your ears.
Where Do Dimples Come From?
If you've ever wondered why some people have dimples and others do not, the zygomaticus muscle plays a role in this common occurrence, too. As explained in the IJAR, natural variations in the zygomaticus muscle between people cause the formation (or absence) of dimples. This phenomenon is actually the result of a birth defect which causes the muscle to split, but fortunately it is one that most people welcome. Interestingly enough, artificial dimples can be created through plastic surgery.
Paralysis of Facial Muscles
Having limited range of motion in your facial muscles can be rather debilitating, both physically and socially. An inability to smile at the appropriate times can easily be misunderstood as a person being disinterested or unhappy when this may not be the case at all. Some of the conditions that can cause this problem include Bell's palsy, trauma, injury during facial surgery, stroke and salivary gland cancer, as explained by The Ohio State University Wexner Medical Center (OSUWMC).
Some of these conditions are only temporary, while others may cause the disruption of normal facial expressions for a lifetime. The OSUWMC recommends seeing a facial nerve specialist if a patient's muscle function does not improve within three to six months. If the problem is caused by a nerve disruption and left untreated for two years, the affected muscles might be permanently damaged.
Your medical professional can help you diagnose the cause of your facial paralysis and advise you on what next steps should be taken to restore your smile. Treatment might include nerve transfers, muscle transfer or botulinum toxin injections, depending on the underlying cause.
Rest assured that if you temporarily lose the ability to smile due to paralysis of your facial muscles, your team of healthcare providers can help you determine the best steps for treatment. And the next time you smile wide, you can thank your zygomaticus muscle for making it happen.