Botulinum toxin is used cosmetically to paralyze the facial muscles. In the jaw, we can use neurotoxins in the masseter muscle. This is one of many muscles that helps us chew, and you can feel it as a deep prominence along your jawline when you clench your teeth down. It is also a muscle that is sometimes tight in individuals who clench their jaw or grind their teeth at night. Injections of botulinum toxin to this area will act to weaken the masseter muscle. Functionally, this improves the pain that some people experience in their jaw and also alleviates uncomfortable night grinding. From a cosmetic perspective, this will also work to slim the muscle and create a more narrow lower face and sleeker jaw appearance. It will take a face that is more rectangular in appearance and create a more V-shaped jawline.