ABSTRACT
Horizontal forehead lines are produced by the action of the anterior frontalis portion of the occipitofrontalis muscle. The frontalis inserts superiorly into the galea and inferiorly into the procerus, corrugator supercilii, orbicularis oculi, depressor supercilii and the skin of the brow. In wishing to treat undesirable horizontal forehead lines, it is important to realize that this muscle is the only brow elevator. For the first-time user it is highly appropriate to treat only the glabella and then to see the patient in 2 weeks and treat only what is necessary in the forehead. An alternative approach is to treat both the glabella and the horizontal forehead lines at a single session. In individuals who have a brow wider than 12 cm between the temporal fusion lines, a fifth or even sixth injection site may be necessary.
