[Morphological studies on lower margins of nasal aperture in the skull of Hokkaido Japanese].

It is well-known that the lower margins of nasal aperture in the human skull may be classified into the following four types, i.e., Forma anthropina, Forma infantilis, Fossae praenasales and Clivus nasoalveolaris, and that the rates of appearance of these four types differ with races. In the present study we made morphological studies on the lower margins of nasal aperture of 465 Hokkaido Japanese skulls, 463 skulls with symmetrical nasal aperture and 2 skulls with asymmetrical one, and compared the findings with those of all races in the world, especially of the Japanese, Ainu, Moyoro Man, Hamanaka Site Man and Eskimo. Forma anthropina was found in 330 skulls (71.27 +/- 2.10%) among the 463, marking the highest rate. Forma infantilis, found in 74 skulls (15.98 +/- 1.70%) among the 463, marked the second highest rate. Fossae praenasales, found in 42 skulls (9.07 +/- 1.33%) among the 463, marked the third highest rate. These 42 cases of Fossae praenasales were further classified into three types, i.e., sub-Forma infantilis, 17 (40.48%), typical Fossae prenasales, 23 (54.76%) and sub-Clivus nasoalveolaris, 2 (4.76%). Clivus nasoalveolaris, found in 17 skulls (3.67 +/- 0.87%) among the 463, marked the lowest rate. As a whole, the rates of the four types in the Hokkaido Japanese were close to those in the other groups of the Japanese in Kinai and Hokkaido (Ito).