The Vermilion Canal: A Longitudinal Potential Space Beneath the Vermilion Margin Explaining One Point, Linear Filler Spread

A consistent longitudinal potential space beneath the vermilion margin can facilitate long-segment, linear filler distribution after single-entry injection. The "vermilion canal" concept offers a simple anatomic explanation for border tracking and may support a streamlined, plane-specific approach for creating a crisp vermilion border line while maintaining vigilance for vascular variability.