Interest in petit plastic surgery including botulinum toxin, filler, and thread lift is increasing. However, serious side effects such as visual loss and skin necrosis may follow even the simplest minimally invasive plastic surgery. Improper treatment techniques can bring undesired outcomes. Many factors affect the surgical outcome but extensive knowledge of the anatomy can help enhance the safety and efficacy of a procedure. In this series, Dr. Yong-woo Lee, a plastic surgeon working in the community healthcare center of Yongin, Korea will introduce facial anatomical knowledge essential for performing minimally invasive (petit) plastic surgery.

 

Forehead

 

Asians view an evenly rounded forehead without angular protrusions as beautiful, although the preferred forehead shapes may differ across cultures. Unfortunately, bilateral frontal eminence exists in the frontal bone from birth. And the supraorbital rim projects forward which can create a hollowness between the frontal eminence and supraorbital rim. Therefore, the key area of the forehead augmentation procedure is the cross shape between two frontal eminences and two supraorbital ridges (Image 1).

 

Image 1. Forehead & Frontalis muscle (STS: Superior Temporal Septum).

 

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Frontalis muscle

 

The frontalis muscle lies above the frontal bone. This muscle is attached to the eyebrow and is an antagonist to the procerus, corrugator supercilii, depressor supercilii, and orbicularis oculi muscles. The galea aponeurotica that includes the frontalis muscle is posteriorly connected to the occipitalis muscle and forms the superior temporal septum (STS) at the border with superficial temporal fascia (Image 1).

In the past, Spiegel et al. reported that the frontalis muscle bifurcates at about 3.5cm above the superior orbital rim. Based on this, the upper-mid portion of the forehead was thought to lack muscle and botulinum neurotoxin was useless in this area. However, such findings were based on gross examination. Costin et al. found cases where the bifurcation of the frontalis muscle occurred higher and those where the frontalis muscle continued without bifurcation. Histological examination of the upper-mid forehead confirmed existence of muscle and disproved the previous reports based on gross examination. This indicated that botulinum neurotoxin may be necessary in the upper-mid portion as well. The depth of the frontalis muscle is around 3-5mm below the skin surface and the horizontal width varied among individuals.

 

-To be continued-