Certain wrinkles are caused by exaggerated muscle tension – these are called dynamic wrinkles. The contracted muscle tends to pull on the skin and create wrinkles. In this case, a minute quantity of botulinum toxin (Botox ®) can be injected into the muscle. Botulinum toxin is a protein produced by the Clostridium botulinum bacteria. It blocks the neural transmission from nerve to muscle, so that muscles contract less easily and are forced to relax. Because the muscle relaxes, the overlying skin will do the same and make wrinkles less visible. Sometimes they even totally disappear. This specifically applies to crow’s feet, frown and forehead wrinkles. It is important to use very small quantities of botulinum toxin, because the Amsterdam Kliniek tries to avoid creating an expressionless “frozen face.”