
The glabella is controlled by muscles responsible for frowning and concentrating. Repeated contraction over time causes vertical lines to form between the brows, which may remain visible even when the face is at rest.
As skin elasticity declines and muscle activity persists, these lines can deepen and create an appearance of tension, fatigue, or frustration that doesn’t reflect how someone feels. Stress and habitual expressions can further accentuate glabellar lines.