Shoib A. Myint - Nonsurgical Peri-orbital Rejuvenation

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Bradley N. Lemke

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The evolving shift towards less invasive procedures for aesthetic facial rejuvenation naturally demands a more sophisticated understanding of facial anatomy. The outcome of any surgical or nonsurgical procedure can be optimized with a detailed understanding of the anatomical framework. An artistic and logical appreciation of the anatomical facial structures and their morphological variations is important in choosing and performing any procedure. This chapter highlights the practical anatomy of the upper and midface relevant to oculofacial cosmetic surgery.

Facial proportions and topography may vary with age, gender, and ethnicity. It is essential to understand the standard basics of these proportions as well as their impact when considering any surgical or nonsurgical cosmetic procedure.

The normal human face extends vertically from the anterior hairline to the chin and is delineated laterally by the auricles. The inferior border of the face, also known as the jaw, is defined by the menton in the midline and the borders of the mandible laterally [].

The shape and prominence of the forehead between the hairline and eyebrows is dependent on the frontal bone framework and the overlying subcutaneous tissue and muscle complex. The glabella is bordered on either side by the eyebrows, which run in an arched manner over the supraorbital rims. The periorbital region is divided into medial and lateral canthal areas and superior and inferior eyelid portions. The cheek lies over the prominent zygomatic bone to contribute to the youthfulness of the face. The cheek convexes anteriorly to merge with the lower lid to form the smooth eyelid-cheek junction. The cheek area is defined anteriorly by the external nose, nasolabial and labiomarginal folds, posteriorly by the anterior margin of the masseter muscle, superiorly by the infraorbital margin, and inferiorly by the mandible. The ideal location of the malar prominence is approximately 10 mm lateral and 15 mm inferior to the lateral canthal angle. Below the malar prominence lies the submalar triangle which is an inverted depressed triangular area of the middle third of the face, delineated superiorly by the zygomatic prominence, medially by the nasolabial fold, and laterally by the masseter muscle [].

The ideal face has been described as five eye widths wide and eight eye widths high, and the normal location and dimensions of important structures are important to understand [].

The skin and the subcutaneous tissue over the face has been broadly classified into periorifacial and cervicofacial skin. The periorifacial skin around the eyes, nose, and mouth is thinnest on the face and has little or negligible subcutaneous fat. The muscle fibers in these areas are firmly adherent to the dermis of the skin and therefore clinically manifest as expression lines.

In contrast, the forehead, cheek, and neck are covered with thick skin with abundant subcutaneous fibrofatty tissue. The superficial musculoaponeurotic system (SMAS) is an example of this thicker cervicofacial tissue. Due to the presence of this thicker skin and subcutaneous tissue layer, these cervicofacial regions are less vulnerable to fine lines and wrinkle formation. The subcutaneous tissue and fat in these areas also define the facial framework and topography by softening bony prominences and filling in natural facial contours [].

The skin in general is composed of the epidermis, dermis, and loose connective tissue with fat. The outermost layer, the epidermis, is composed of four distinct layers(1) keratinized and impermeable stratum corneum, (2) stratum granulosum, (3) vascular stratum spinosum, and (4) the cellular stratum basal (keratinocytes, melanocytes, fibroblasts) [].

The underlying dermis consists mainly of collagen and some elastic fibers (5 %). Approximately 5001,000 m thick, the dermis provides structural support to the epidermis and determines the thickness and elasticity of the skin. Dermal regeneration of the epidermis with any form of treatment like dermabrasion, laser resurfacing, or chemical peels depends on the integrity and function of the adnexal structures of the dermis. The dermis is subdivided into the superficial loose vascular layer of connective tissue called the papillary dermis and the deeper reticular layer rich in collagen and elastic fibers. To optimally correct wrinkles and scars with skin rejuvenation procedures, the dermal layer needs to be targeted to the appropriate depth based on the structure to be treated. Vascular lesions like port wine stains and telangiectasis are mainly dermal and can be minimized with dermal treatments. The dermis layer is compact, highly vascular, and also rich in nerve endings. Therefore, penetration of a needle into the dermal layer may meet resistance, be painful, and may cause superficial bruising.

The subcutaneous layer located beneath the dermal layer comprises primarily lobules of fatty tissue. Its thickness and presence of fascial connections are vital to the youthful face and are later important for volumetric analysis in the aging face.

The subcutaneous layer also functions as a buffer for skin trauma, as areas with abundant subcutaneous tissue often heal faster and with less scaring than areas with thin or no subcutaneous tissue. Therefore, deep dermal penetration in areas of the face with almost no subcutaneous tissue, such as the lips, jawline, and neck, should be carefully approached. Dermal thickness in the nasolabial fold is approximately 1.321.55 mm. The diameter of the needle used to inject dermal fillers ranges between 0.3 and 0.4 mm with the length of the bevel being approximately 0.750.95 mm [].

The face comprises the forehead, eyebrows, eyelids, cheek, and lower face subunits that are all closely interrelated. The face is enveloped by the superficial musculoaponeurotic system (SMAS), first described by Mitz and Peyronie []. The SMAS is a fibrous fascial tissue, extending from the temporalis and frontalis muscles superiorly to the platysma inferiorly, that interconnects the facial muscles. Intraoperatively, it can be identified as a shiny fibrous layer located between the dermis and deep fascial muscles. Superiorly the SMAS is densely adherent to the zygomatic arch and the temporalis fascia and inferiorly interdigitates with the dermis in the cheek, platysma over the mandible, and the sternomastoid muscle fascia in the neck. The motor branches of the facial nerve lie deep to the SMAS. Because of its bony and soft tissue attachments, the SMAS acts as an important distributor of facial muscular contractions to the skin.