Glabellar Region Anatomy
Frown lines, or glabellar lines, are dynamic wrinkles between the eyebrows caused by contraction of the corrugator supercilii and procerus muscles. Located in the glabella—the area between the inner eyebrows—these lines create an angry or concerned expression and are among the first facial signs of aging. They develop from habitual facial expressions and become increasingly prominent with age.
Muscle Physiology
The corrugator supercilii muscles pull the medial eyebrows downward and inward, creating vertical wrinkles. The procerus muscle, located at the nasal bridge, creates horizontal lines above these vertical folds. Repeated contraction from frowning, concentrating, or squinting progressively deepens these lines. Genetic predisposition influences individual susceptibility to glabellar line development.
Botox Injection Protocol
Glabellar lines require 16-25 units of Botox injected into the corrugator supercilii and procerus muscles. Standard injection sites include three points: two corrugator injections at the medial eyebrow and one procerus injection at the nasal bridge. Injections are placed intramuscularly at a depth of approximately 8-10 mm. Proper technique prevents migration into the medial forehead or upper eyelid.
Anatomical Considerations
The supratrochlear artery runs medially in the glabellar region, requiring awareness of vascular anatomy to minimize hematoma risk. The injection sites lie above the medial canthal tendon. Practitioners must avoid injecting too medially or deeply, which could affect the corrugator supercilii and cause unwanted brow elevation asymmetry. Conservative dosing in the glabella is essential to maintain natural expression.
Expected Results
Glabellar lines soften within 3-7 days and completely resolve by day 14. Successful treatment eliminates the angry or scowling appearance, creating a more approachable facial expression. Dynamic frown lines virtually disappear during facial expressions. Some static lines may persist if the skin has lost significant elasticity, potentially requiring adjunctive dermal filler treatment. Results last approximately 3-4 months.
Combination Therapy
Glabellar Botox is frequently combined with forehead and crow's feet treatment for comprehensive upper facial rejuvenation. Adding filler to static glabellar lines can enhance results in patients with deep, persistent creases. This combination approach addresses multiple signs of facial aging simultaneously, providing harmonious, balanced facial rejuvenation.
Safety and Complications
Glabellar injection carries a very low complication rate when performed by experienced practitioners. Potential complications include temporary eyelid droop if injected too low, or asymmetrical eyebrow position if dosing is uneven. Overcorrection can result in a frozen, unnatural appearance. These complications are temporary and resolve within 8-12 weeks as the toxin wears off.