WP Chung O T in Facial Aesthetic Surgery_9781496349231

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Injection of Botulinum Toxin to the Glabellar Region Section I: Techniques for Botulinum Toxins in the Face

C H A P T E R

Jonathan Sykes, Peter Palhazi, and Amir Allak

DEFINITION

■ The CS muscle body is pierced by the supraorbital and supratrochlear neurovascular bundles carrying sensory input to the trigeminal nerve (V1). The nerves then pierce the frontalis muscles approximately 2 to 3 cm above the supraorbital rim to travel subcutaneously to the forehead and scalp ( FIG 2 ). ■ The medial head of the CS has motor innervation from the zygomatic branch of the facial nerve, whereas the lat- eral portion is supplied by the temporal branch of the nerve. ■ Contraction of the muscle causes vertical grooves in the gla- bellar skin and imparts an angry expression. Contraction also causes an inferomedial descent of the medial clubhead of the brow. ■ The procerus is a midline flat and pyramidally shaped mus- cle located at the root of the nose contributing to upper nasal contour. ■ The procerus originates from the periosteum and perichon- drium of the nasal bones and upper lateral cartilages and from the fascia of the nasal superficial musculoaponeurotic system (SMAS) (see FIG 2 ). ■ Procerus inserts into the midline skin overlying the nasal root and interdigitates superiorly with the frontalis muscle (see FIG 2 ). ■ The motor innervation to the procerus is supplied by the zygomatic branch of the facial nerve. ■ Contraction of the midline muscle is responsible for hori- zontal glabellar rhytids, transverse rhytids on the nasal dor- sum, and descent of the medial brow.

■■ Hyperfunctioning of muscles in the periorbital region results in a tired, aged appearance and increased rhytids. ■■ Hyperdynamic glabellar musculature can create an angry appearance, whereas overuse of the lateral eyelid muscles can narrow the eyelid aperture. ■■ The position and orientation of the eyebrow is related to the relative strength and contraction of the brow depressors vs the brow elevators. ■■ The only elevators of the eyebrow are the paired frontalis muscles, whereas depression of the eyebrow is accomplished by contraction of the midline procerus muscles, the paired corrugator, and orbicularis oculi muscles. ■■ Treatment with botulinum toxin can lessen the contraction of hyperdynamic periorbital muscles and can improve the eyelid aperture, improve brow position, and decrease peri- orbital rhytids. 1 ANATOMY ■■ The corrugator supercilii (CS) are paired, obliquely oriented muscles located in the inferomedial brow deep to the infe- rior portion of the frontalis muscles. ■■ The CS muscle originates from the bony superomedial orbital rim and passes in a superior and lateral direction to insert onto the fascia of the frontalis muscle and into the overlying skin ( FIG 1 ). ■■ In addition to coursing superiorly and laterally from its inser- tion, the CS becomes more superficial as it travels laterally.

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FIG 2 • Cadaveric dissection with coronal forehead flap elevated viewed from the superior aspect of the head. L, patient’s left; R, patient’s right; SO, supraorbital neurovascular bundle; ST, supratrochlear neurovascular bundle; NR, nasal root (indicating midline); PM, procerus muscle.

FIG 1 • Cadaveric dissection of the relationship of the corrugator muscle to the nasal root and frontalis. CS, corrugator supercilii.

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