Prosthion

Japanese: Prosthion

…The facial index is calculated by dividing the facial height (from the boundary between the frontal bone and the nasal bone, Nasion, to the median lower edge of the mandible, Gnathion) by the width of the buccal arch (the width connecting the points where the left and right buccal arches protrude laterally). The height from the Nasion to the most anterior point of the upper alveolus, Prosthion, is called the upper facial height, and this is used to calculate the upper facial index. Depending on the upper facial index, the face is classified into a wide upper face type (less than 49.9), a medium upper face type (50.0 to 54.9), and a narrow upper face type (55.0 or more). …

From [Facial angle]

…The angle between the contour and the auricular plane (the plane determined by the upper margins of the external auditory canals on both sides, Porion, and in living organisms, the upper margin of the ear cartilage, Tragion, and the lowest point of the left orbital entrance, Orbitale) is calculated. The angle between the line connecting the boundary point between the frontal bone and the nasal bone, Nasion, and the anteriormost point of the upper alveolus, Prosthion, and the auricular plane is called the total lateral angle. Depending on the size of this angle, it is classified as prognathic (less than 79.9°), degnathic (80.0° to 84.9°), or orthognathic (85.0° or more). …

*Some of the terminology that mentions "Prosthion" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…頭蓋骨では顔面高(前頭骨と鼻骨の境界点Nasionから下顎骨の正中下縁Gnathionまで)を頰骨弓幅(左右の頰骨弓が側方に突出した点を結ぶ幅径)で割った値を顔示数という。またNasionから上側歯槽の最前点Prosthionまでの高さを上顔高といい，これを用いて上顔示数を算出する。上顔示数の数値によって広上顔型(49.9未満)，中上顔型(50.0～54.9)，狭上顔型(55.0以上)に分類する。…

【顔面角】より

…輪郭が耳眼平面(左右の外耳孔上縁点Porion，生体では耳軟骨の上縁Tragionと左側の眼窩入口の最低点Orbitaleによって決定される面)と交差してなす角を求める。この時に前頭骨と鼻骨の境界点Nasionと上側歯槽の最前点Prosthionとを結ぶ直線が耳眼平面となす角を全側面角という。その大きさによって，突顎(79.9゜未満)，中顎(80.0゜～84.9゜)，正顎(85.0゜以上)に分類する。…

※「Prosthion」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典第２版について | 情報

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