Muscles that act on glabellar skin: a closer look.

The coronal incision forehead lift became a component of the face-lift procedure 35 years ago and increased the cosmetic benefit for the facial aesthetic surgery patient. Later, this enhanced cosmetic effect achieved from eyebrow resuspension was complemented by treatment of the glabellar skin lines by modifying corrugator supercilii and procerus muscle function through the same coronal incision. In recent years, newer procedures for treating the corrugator supercilii and procerus muscles by using endoscopy or limited incision techniques have eliminated the need for the coronal incision. With these newer techniques has come a renewed interest in the surgical anatomy of the muscle complex that acts on glabellar skin. This study was designed to examine the current understanding of the anatomy of these muscles and to resolve misconceptions and controversy concerning them. Fresh cadaver dissections and simulated muscle action studies done on the glabellar musculature of four specimens were correlated with nerve blockade studies performed in 10 subjects on the temporal and zygomatic branches of the facial nerve. The presence of the depressor supercilii muscle as a distinct entity was confirmed. The little-appreciated oblique head of the corrugator supercilii muscle was identified. The conclusions from this study suggest that the transverse head of the corrugator supercilii muscle produces the vertical component of the glabellar skin line and also contributes to the formation of the oblique component of the glabellar skin line. The oblique head of the corrugator supercilii muscle, the depressor supercilii muscle, and the medial head of the orbital portion of the orbicularis oculi muscle all appear to depress the medial head of the eyebrow and contribute to the formation of the oblique glabellar skin line. The nerve block study provided evidence that the zygomatic branch of the facial nerve supplies the three medial eyebrow depressor muscles, which opens the possibility for future nerve ablation techniques to control the action of the medial eyebrow depressor muscle group. This nerve block study also supports the concept of "physiologic" elevation of the medial eyebrow as an effective component of foreheadplasty.