When you chew food, smile or make any facial expressions, it's a sign that your facial muscles are working hard. The majority of your facial muscles play the important role of helping you express emotions, as StatPearls explains.
Within this muscle group is the mentalis muscle, which lets you lower and raise your bottom lip. Some facial muscles, such as the mentalis, may seem small and insignificant — but without them, you'd miss out on a lot. Just think about going through life without the ability to pout or smile and you'll soon understand just how vital this muscle can be for social interactions in daily life.
Where Is the Mentalis Muscle?
Put two fingers on your chin and you'll most likely be placing your fingers over the mentalis muscle. As illustrated by the Loyola University Medical Education Network, the muscle comes out of your mandible, or lower jawbone, in the front of your face. It attaches to the soft tissue of your chin and stretches from the lower lip down along the vertical length of your chin. The muscle is a "paired muscle," meaning it's divided into two parts, as noted by the Atlas of Oral and Maxillofacial Surgery.
The muscle is controlled by the mandibular branch of the facial nerve, which innervates the muscles in the lower part of the face, as StatPearls points out. The facial nerve has a big job to do, as it provides sensation to your tongue, helps your body produce tears and controls the movements of the muscles that allow you to grimace, pout, smile and express a range of emotions.
What Does the Muscle Do?
Fun fact about the mentalis: Its name is supposedly drawn from the part it plays in helping you make "thinking" facial expressions. It's sometimes called the pouting muscle, as well, because it helps you lift up and stick out your lower lip. According to Loyola University Medical Education Network, your mentalis also plays a role in creating dimples or wrinkles on your chin, which can tell the world around you that you're deep in thought or are carefully contemplating an issue.
Problems With the Mentalis
Cosmetic ConcernsTypically, the mentalis doesn't cause people any serious problems, but it can sometimes cause cosmetic concerns. One such problem is that repeated movement of the muscle over time can cause the chin to develop into an abnormal shape. If someone has an underprojected chin caused by an overactive mentalis and wants to correct it, one option is for a plastic surgeon or dermatologist to inject onabotulinumtoxin A into the area. A study published in JAMA Facial Plastic Surgery showed that people with overactive mentalis muscles saw an improvement in the appearances of their chins after receiving these injections.
GeniospasmInvoluntary contractions of the muscle may be attributed to a condition called geniospasm. This condition, which is thought to be hereditary, is extremely rare and only occurs in about 500 people worldwide, as a study published in the Journal of Clinical Sleep Medicine notes. Although geniospasm is often considered benign, there have been a few cases where the issue has caused discomfort and other symptoms, such as tongue biting.
If you can pout without trouble and don't have an abnormally shaped chin, the odds are likely that you don't have any problems with your mentalis muscle. But if you are concerned about the muscle or notice that your chin trembles more than seems normal, remember that your medical and dental professionals are there to diagnose and treat any problems you encounter or refer you to the appropriate specialist when necessary.