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Abstract: This study aimed to examine the accurate location and boundary of the parotid gland in Koreans.Forty hemifaces from embalmed cadavers (mean age: 73 years) were studied. The line connecting the porion, gonion, and gnathion was used as a reference line. To measure the boundary of the parotid gland, the Frankfort horizontal line was used as the x-axis, whereas the vertical line passing through the porion was used as the y-axis. All measurements were taken from the lateral side of the face.The parotid gland has a variety of shapes: irregular, reverse triangle, and falciform. In all specimens, the boundary of the parotid gland was located 20 to 60 mm below the Frankfort horizontal line and located 10 mm anterior to the y-axis. On average, the most anterior and posterior distances of the parotid gland from the porion-gonion line were 36.4 ± 13.9 mm and 20.1 ± 10.5 mm, respectively, and the most inferior distance of the parotid gland from the gonion-gnathion line was 9.8 ± 5.8 mm. All specimens of parotid glands were found within an area 20 to 40 mm below the Frankfort horizontal line and 10 mm to the left of the y-axis. The most anterior point of the parotid gland was observed at varying locations. The maximum value of the most anterior point was 61.26 mm; it rarely exceeded the ectocanthion. The most posterior points of the parotid gland were located between the mastoid process and sternocleidomastoid muscle.These results might be useful for preventing injury to the parotid gland during facial rejuvenation procedures., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 by Mutaz B. Habal, MD.)

Abstract: The aim of this study was to elucidate the relationships between the nasolabial fold and superficial fascia on histology and P45 sheet plastination.Two centimeter width specimen of the nasolabial area were harvested from the skin to periosteum. Then, 10-μm sections were made, stained with Masson trichrome, and observed under a light microscope. Three head and neck specimens were sliced in horizontal sections (46 slices) using P45 sheet plastination (polyester resin corrosion-resistant method designed to preserve biological sectional specimens in situ). Through slicing, bleaching, dehydration, casting, forced impregnation, curing, cutting, and sanding the molds, P45 plastination provided good light transmission, allowing the internal structures within the sheet to be revealed clearly in their intact form.The observations on histology and P45 sheet plastination correlated well. The nasolabial fold consisted of the superficial fatty layer of superficial fascia (SFS). At the beginning of the alar groove level, the nasolabial groove was located on the point where the medial limit of SFS met the levator labii superioris. At the alar base level, the nasolabial groove was located where the medial limit of the SFS met levator labii superioris. At the mouth corner level, the nasolabial groove was located where the medial limit of the SFS met the modiolus, including the orbicularis oris. The superficial fascia became scanty near the nasolabial groove, and the SFS comprised the nasolabial fold.The results of the present study may be helpful for applying subcutaneous dissection or sub-superficial muscular aponeurotic system dissection in rejuvenation of the nasolabial area., Competing Interests: The authors report no conflicts of interest., (Copyright © 2020 by Mutaz B. Habal, MD.)

Abstract: In this paper, the authors attempted to determine the extent of the superficial fascia of the cheek using P45 sheet plastination.Three head and neck specimens were sliced in horizontal (46 slices), coronal (30 slices), and sagittal (29 slices) sections using P45 sheet plastination (special polyester resin corrosion-resistant method designed to preserve biological sectional specimens in situ). Through slicing, bleaching, dehydration, casting, forced impregnation, curing, cutting, and sanding the molds, P45 plastination sheets provided good light transmission, allowing the internal structures within the sheet to reveal clearly in their intact form.P45 sheet plastination revealed that the superficial fascia in the cheek area is generally composed of 3 layers: a superficial fatty layer, a membranous layer, and a deep fatty layer. Anteriorly, the membranous layer of superficial fascia (MSF) extended to the posterior border of the zygomaticus major muscle, enveloping this muscle, and then to the lateral border of the orbicularis oculi muscle. Posteriorly, the MSF extended to the anterior border of the parotid gland, and then was continuous with the parotid fascia. Superiorly, the MSF extended to the line from the tragus to the alar base. Inferiorly, the MSF extended to the line from the mandibular angle to the mouth corner. Below this line, the SMAS continued to the upper border of the platysma muscle.Our results using P45 plastination concorded well with Mitz's original drawing. We suggest that the results of the present study may be helpful for practicing surgeons to apply in subcutaneous dissection or sub-SMAS dissection in facelift procedures., Competing Interests: The authors report no conflicts of interest., (Copyright © 2020 by Mutaz B. Habal, MD.)