WP Chung O T in Plastic Surgery

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Part 1 Facial Aesthetic

deep branch that runs between the periosteum and the deep- est layer of galea and then pierces the frontalis near the hair- line to innervate scalp skin. 5 Motor Nerves ■■ The temporal branch of the facial nerve is the only motor nerve of surgical concern in this area. The tempo- ral branch enters the temporal fossa as several (2–4) fine branches that lie on the periosteum of the zygomatic arch in its middle third. Between 1.5 and 3.0 cm above the arch, these branches become more superficial, traveling within the superficial temporal fascia (temporoparietal fascia) to innervate the frontalis, superior orbicularis, and glabellar muscles. 6 A number of different landmarks can be used to predict the course of the temporal branches. These include ■■ The middle third of the palpable zygomatic arch ■■ 1.5 cm lateral to the tail of the eyebrow ■■ Parallel and adjacent to the inferior temporal septum ■■ Immediately superior to the medial zygomaticotemporal vein (sentinel vein) ■■ In the coronal brow lift procedure, the dissection should be entirely deep to the temporal branches of the facial nerve. ■■ The periorbital region is the most expressive part of the human face. Subtle changes in eyebrow shape can pro- foundly affect facial appearance. 1 ■■ Because of the importance of periorbital expression, humans have historically resorted to any means at their disposal to alter their eyebrows. These have included eyebrow plucking and shaving, makeup, and tattoos. ■■ Aesthetically, the eyebrow is only one part of the puzzle in the periorbital zone. Other variables include the presence of senile eyelid ptosis, the loss of upper sulcus orbital fat, and the accumulation excess of upper eyelid soft tissue (skin, orbicularis muscle, and orbital fat). ■■ The preferred forehead will be devoid of vertical of trans- verse lines. It will be framed superiorly by a well-positioned aesthetically shaped hairline and inferiorly by well-posi- tioned, attractively shaped eyebrows. ■■ The “ideal” eyebrow shape is affected by ethnicity, gender, and the era in which we live ( FIG 2 ). There are certain themes that define aesthetically pleasing eyebrow in the 21st century: 7 ■■ The medial eyebrow level should lie over the medial orbital rim. ■■ The medial border of the eyebrow should be vertically in line with the medial canthus. ■■ The eyebrow should rise gently, peaking slightly at least two-thirds of the way to its lateral end; typically, this peak lies vertically above or lateral to the lateral limbus. ■■ The lateral tail of the brow should be higher than the medial end. ■■ The male brow should be lower and less peaked. ■■ Abnormally low eyebrows can be congenital or acquired over time through aging. ■■ Age-related brow ptosis causes the forehead/eyebrow com- plex to encroach on the upper orbit, resulting in a pseudoex- cess of upper eyelid skin. In response, patients subconsciously contract the frontalis to raise the eyebrows, leading to trans- verse forehead lines. This is accentuated with the presence of mild senile eyelid ptosis. Such patients will often present with a request for upper lid blepharoplasty. PATHOGENESIS

layer is the so-called glide plane space, which allows the scalp flap to shift superiorly. ■■ The galeal fat pad extends across the entire width of the lower 2 cm of the forehead; medially it encompasses the supratroch- lear nerves and much of the corrugator musculature. The galeal fat pad is separated from the preseptal fat (retro-orbi- cularis oculi fat or ROOF) by one of the layers of galea (see above). Laterally, this galeal layer is thought to be inconsistent, with some individuals having continuity between the galeal fat pad and the preseptal fat (ROOF). Within the eyelid, the sep- tum orbitale divides the preseptal fat (ROOF) from orbital fat. ■■ Muscle anatomy plays a significant role in determining eyebrow shape and position. In addition to the soft tissue attachments, the level of the eyebrow is the result of a bal- ance between the muscular forces that elevate the brow, the muscular forces that depress the brow, and gravity. ■■ Brow depressors in the glabella originate from bone and insert into soft tissue. The procerus runs vertically near themidline, the depressor supercilii and supramedial orbicularis run obliquely, and the corrugator supercilii runs mostly transversely. ■■ The transverse corrugator supercilii is the largest and most significant of these muscles. Useful landmarks to locate the corrugator are as follows: the corrugator originates from the orbital rim at its most superomedial corner, right at the entrance to the orbit. The transverse head passes through galeal fat becoming more superficial until it interdigitates with the orbicularis and frontalis under a skin dimple that is visible when the patient frowns. ■■ The orbicularis encircles the orbit acting like a sphincter. Medially and laterally, the orbicularis fibers run vertically and act to depress brow level. Laterally, orbicularis is the only muscle that depresses brow position. ■■ The frontalis is the only elevator of the brow. It originates from the galea aponeurotica superiorly and interdigitates inferiorly with the orbicularis. Contraction raises this muscle mass and the overlying eyebrow, which is a cutaneous struc- ture. The muscle is deficient laterally, so its primary lifting effect is on the medial and central portions of the eyebrow. Sensory Nerves ■■ Innervation to the upper periorbita is supplied by the supra- orbita and supratrochlear nerves, as well as two lesser nerves, the infratrochlear and zygomaticotemporal. ■■ The zygomaticotemporal nerve exits posterior to the lateral orbital rim piercing the deep temporal fascia just inferior to the sentinel vein. In coronal brow lifting, with com- plete release of the lateral orbital rim, it is often avulsed. Consequences of this are minimal and temporary. ■■ The supratrochlear nerve usually exits the orbit superomedi- ally, although the exact location is variable. It immediately divides into four to six branches that usually pass through the substance of the corrugator. These branches then travel superiorly, on the superficial surface of the frontalis, innervat- ing the central forehead and first few centimeters of the scalp. ■■ The supraorbital nerve exits the superior orbit through a notch in the rim, or about 10% of the time, through a fora- men that is superior to the rim. ■■ The supraorbital nerve divides into two segments: super- ficial and deep. The superficial branch pierces orbicularis and frontalis, traveling as several small branches on the superficial surface of the frontalis to innervate the central forehead as far posteriorly as the first 2 cm of hair. The rest of the scalp, as far back as the vertex, is innervated by the

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