arTICle | boTulInum ToxIn A |
animation and spontaneous expression. These differences in glabellar wrinkle patterns indicate that the strength of each glabellar muscle is not identical and uniform in every patient and one set of muscles may be stronger or weaker than its co-depressor set of muscles. Their response to neurostimulation also is uniquely different in every individual. Therefore, the pattern of glabellar frowning is dependent upon which muscles are stronger or weaker, and the injected dose of onabotulinumtoxinA must vary accordingly. Some glabellar wrinkle patterns are observed more frequently than others according to Trindade de Almeida(15) (Figure 2).
Functional anatomy Contracting any of the mimetic muscles of the face will cause wrinkling of the skin perpendicular to the orientation of those muscle fibers and the direction of their movement. Therefore, the muscles that produce the vertical lines of the glabella because their fibers are oriented more or less horizontally are the medial brow depressors, i.e. corrugator supercilii, and the medial fibers of the orbital orbicularis oculi. The corrugator supercilii is a small, narrow, deeply
Figure 1 (A) This 28-year-old patient with relatively flat arches before treatment. (B) After treatment, the eyebrows are elevated and arched with strategically placed onabotulinumtoxinA. Note the right eyebrow also is slightly lifted
The brow has both static and dynamic qualities of
beauty and expressiveness that change with age*I. This is seen as brow ptosis in varying degrees, which can modify the shape and position of the brows, thereby compromising the youthful appearance and aesthetic attractiveness of a person. The pre-treatment position and symmetry of the
eyebrows and eyelids will dictate the technique that will be needed to treat the glabellar frown lines. In women whose eyebrows are barely arched, strategically placed injections of onabotulinumtoxinA into the brow depressors, can elevate the eyebrows by allowing the lower fibers of the frontalis to raise the eyebrows unopposed by the decussating fibers of the corrugator supercilii, procerus and orbicularis oculi *A (Figure 1). Trindade De Almeida has
situated paired muscle that arises just inferior to the medial aspect of the superciliary arch approximately 4mm lateral to the nasion. The nasion is the point of juncture of the nasofrontal with the internasal bony sutures (16). Clinically it can be palpated as the center of the concavity at the nasal radix (or root). The corrugator supercilii extends laterally and upwardly through the palpebral and orbital fibers of the orbicularis oculi, inserting into the soft tissue and skin above the middle of the eyebrow in the vicinity of the midpupillary line and the supraorbital notch . The bulk of the corrugator supercilii can be found overlying the inferior aspect of the superciliary arch(16-17) (Figure 3a). It lies directly against the bone and just beneath the interdigitating muscle fibers of the orbicularis oculi, procerus, depressor supercilii, and frontalis medially and beneath interdigitating fibers of the frontalis and orbicularis oculi laterally. Anatomic studies have demonstrated that the thickest portion of the belly of the corrugator is at or just above a horizontal plane drawn through the middle of the eyebrow and approximately 2.0 cm from the nasion(14,16,18) (Figures 3a & b). The outermost fibers of the
The pre-treatment
position and symmetry of the eyebrows and eyelids will
classified glabellar frown lines into five distinct patterns(15). Although the muscular anatomy is by and large alike in most patients, individual skeletal morphology and idiosyncratic muscular movements can produce unique variations in the pattern of wrinkles in the glabellar area as well as anywhere else on the face during intentional
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dictate the technique that will be needed to treat the glabellar frown lines.
orbicularis oculi are called the orbital portion of the orbicularis oculi. The orbital orbicularis oculi arises from the bony structures of the lateral nose and medial orbit, including the medial canthal ligament. Its fibers then run superiorly and inferiorly, forming a wide sphincteric ring around
the bony orbit that extends beyond the edges of the bony orbital rim and into the eyelids. This inner portion of the orbicularis oculi that overlies the eyelids and is identified as the palpebral portion of the muscle. The medial aspect of the orbital orbicularis oculi
Figure 2 Glabella: patterns of contraction. Five subtypes: (A) “U” pattern, (B) “V” pattern, (C) “Omega” pattern, (D) “opposing lines” pattern, and (E) “inverted Omega” pattern;three patterns with depression of medial brow (A, B, and E); one with elevation of medial brow (C); one with predominantly horizontal
movement (D). Source: Courtesy of Trindade de Almeida
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