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.