The upper lip is subject to a variety of lines and wrinkles as one ages, particularly in females. The vertical lines of the upper lip are the most recognized and are due to the activity of the sphincteric orbicularis muscle. Another type of aging line is that of the horizontal upper lip crease. While less common, it is also due to hyperactive muscle action of which the depressor septi nasii muscle has been implicated at its cause.
Yet injections of Botox into the depressor septi nasi muscles does not cause the upper lip crease to be improved, suggesting other lip muscles are at fault. Or at least the creation of the upper lip crease involves a more complex interaction of other lip muscles than is currently thought.
In the October 2017 issue of the European Journal of Plastic Surgery an article entitled ‘Prevalence of Transverse Upper Labial Crease’ was published. In this article, the authors studied one hundred (100) females to determine the presence and location of an upper labial crease at rest and smiling. In women over 40 years of age over one-third had an upper lip crease at rest and nearly three-quarters had it with smiling. The location of the crease varied from at the columellar base to the lower third of the lip. It occurred most commonly in women with a ‘big’ smile due to a strong levator labii superior muscle action. Therefore the injection of Botox is proposed as a method to treat the aesthetically undesirable upper lip horizontal crease.
The levator labii superioris is a muscle of facial expression that elevates and everts the upper lip. Its origin is from a bony attachment at the superior edge of the upper jaw (maxilla) and descends inferiorly into several slips of muscle into the upper lip. Multiple insertions for these muscle slips have been described from the nostril medially to the zygomatic head laterally. Looking at the length of many upper lip labial creases, it makes anatomic sense that the more central depressor septi nasii muscle can not account for the full length of the lip crease.
This anatomic description for the basis of upper lip horizontal skin creases can be easily tested by injecting Botox into its insertion points. As the authors have stated this does create some lessening of upper lip creases. By weakening of the upward pull of this muscle the patient should be aware that their smile arc may not be as great and the upper lip have increased lengthening.
Dr. Barry Eppley