PURPOSE: To quantify the frontalis muscle action. METHODS: The motion range of the eyebrow was measured in 81 normal subjects divided into three age groups: 20 children (ages from 6 to 12 years), 33 adults (ages from 20 to 38 years) and 28 elderly (ages from 60 to 80 years). Measurements were made using digital image processing analysis. For each subject an image of the subjects' face was obtained with the brow in its resting position. A second image was taken with maximal frontalis contraction. The frontalis action was taken as the difference between the position of the brow with and without frontalis contraction. All measurements were performed at halfway between the medial and lateral canthi. RESULTS: Brow motility in the central part of the lid fissure ranges from 7.57 to 9.02 mm. Despite a clear tendency to increase in brow motility with age, the differences between the age groups were not significant. CONCLUSIONS: The magnitude of the excursion of the central portion of the brow does not depend on age.
Facial muscles; Muscle contraction; Oculomotor muscles; Eyelids; Eyebrows
