Frontalis Muscle Variation
your friendly, neighborhood forehead muscle
The frontalis is a muscle that elevates our eyebrows. As the frontalis contracts, it pulls up our brows, creating dynamic (expression-based) wrinkles across the forehead. Because frontalis muscle fibers are vertical, frontalis contractions form horizontal(ish) wrinkles.
NOTE: Wrinkles form perpendicular to the direction of muscle fibers.
the many faces of frontalis
When we raise our eyebrows, there are numerous wrinkle shapes that can form. Those wrinkle shapes are directly related to our frontalis muscle shape, size, placement, and relationship to neighboring facial muscles.
- Are the wrinkles full lines spanning across the forehead?
- Are the wrinkles displayed in one or more columns?
- Are the wrinkles straight or curved?
getting past cookie-cutter diagrams
Contrary to most anatomy diagrams, the frontalis is widely variable in shape, size, and location. Most illustrations of frontalis tend to display one frontalis shape – the large, bifurcated shape.
NOTE: Bifurcation simply refers to the split in the muscle.
The popular frontalis shape displayed above features:
- the frontalis muscle with a division in the middle
- the frontalis muscle with large sections at each side of the split
- the split connected by a wide, sheetlike tendon referred to as galea aponeurotica (or aponeurosis epicranialis or epicranial aponeurosis)
HOWEVER! The mainstream frontalis shape is by no means the only frontalis shape that exists. Your forehead is a site of diversity.
reframing the frontalis
After analyzing many cadaver photos, studying forehead facial movements, and hunting through research papers, I have created a set of frontalis shape illustrations below. These illustrations are simplified to give you a general idea of the different shapes, sizes, and orientations your frontalis muscle can assume.