Radiologic Measurement of the Nasal Length and Keystone Area in Relation to Nasal Bony and Septal Cartilaginous Dimensions in Korean Adults

Anatomical and Radiologic Analysis of Keystone Area of Korean Nose / 체질인류학회지

The keystone area of nose is a clinically important structure for maintaining the stability of dorsum of nose. However, anthropometric data for individual structure constituting the keystone area were less studied. Dissections of external nose were performed in 12 cadavers for measuring the length and width of structural components of keystone area. Shape of nasal bones and the overlap area between upper lateral cartilage and nasal bonewere classified. Measurements of the keystone area were also performed in 380 MRI and PACS images. Types of the caudal margin of nasal bone were classified as follows; type A: flat margin, type B: M shape, type C: extended midline, type D: retracted midline. Types of overlapped portion between upper lateral cartilage and nasal bone were categorized as follows; type Ao: flat midline, type Bo: short elongated midline, type Co: long elongated midline. Overlap length of upper lateral cartilage with nasal bone was 4~9 mm (mean 6.5 mm)in the midline, 0~4.5 mm (mean 2.7 mm)in the paramedian area of nasal bone. Overlapped width of upper lateral cartilage with nasal bone was 8~14 mm(mean 9.7 mm). Individual component of the keystone area has various shape and overlapped length. Therefore, cautious preoperative and intraoperative evaluation of each component is necessary for a safe nasal surgery.

An Anatomic Study on the Overlap Patterns of Structural Components in the Keystone Area in Noses of Koreans

OBJECTIVES: The keystone area has critical importance in maintaining the stability of the nasal dorsum. However, overlap patterns between structural components in the keystone area have rarely been studied, especially in the noses of Koreans. METHODS: Dissections were performed on 18 cadaveric noses. The length and width of the structural components in the keystone area were measured. The shape of the caudal margin of the nasal bone and the overlap patterns between the upper lateral cartilage and the nasal bone were classified. RESULTS: The shape of the caudal margin of the nasal bone were classified as follows: type A, curvilinear margin; type B, paramedian retractions or "M" shape; type C, elongated midline; and type D, retracted midline. The overlap area between the upper lateral cartilage and the nasal bone was classified as follows: type Ao, crescent shape; type Bo, short midline extension; and type Co, long midline extension. The cephalocaudal length of the overlap area between the upper lateral cartilage and the nasal bone was 4-10 mm (mean, 7 mm) in the midline, and 0-7 mm (mean, 3.1 mm) in the paramedian area. The overlap width of the upper lateral cartilage with the nasal bone was 8-14 mm (mean, 9.7 mm). CONCLUSION: The overlap pattern of the structural components in the keystone area is variable. Therefore, a thorough understanding and a cautious evaluation of the relationships of these components before and during surgery is important in performing safe and effective nasal procedures.