Depending on the photographic approach and the headband, one hundred sixty four subjects, including eighty two male students and eighty two female students, were examined to measure the angle of rotation, which is formed by the longitudinal axis of the external ear and the line of the bridge of the nose. They ranged in a age from 19 to 22 years with a mean of 20.9 years. None of them were evaluated for aesthetic surgery. The following results were obtained: 1) The hypothesis which postulates the longitudinal axis of the external ear is paralled with the line of the bridge of the nose, was not supported. 2) For the male group, the mean and the standard deviation of the angle of rotation were 16.0°±5.7°. 3) For the female group, they were 14.6±6.1°. 4) For the total group, they were 15.3±6.07°.
Purpose: When reconstructive operations of the congenital or acquired external ear defects are performed, newly-designed external ears are situated at certain angle of rotation around the external auditory meatus. However, very few findings of the methods measuring the angle of rotation have been reported. Therefore, in this paper one of the methods mentioned above is studied and described.
Method: Photographical approach using profile view of all subjects was adopted, because of its reasonable reliability and simplicity. At first, a small-sized single lens reflex camera with a telephoto lens of focal distance 100 mm, was set up along the imaginary line connecting subject's left external auditory foramen and her (his) right external auditory foramen. The distance from the camera to the right side face of the subject was approximately 150 cm.
Next, with the help of headband which was worn beforehand, the camera was carefully adjusted to be able to see through two horns of the headband. This adjustment was continued, until the right horn could hide the left horn. Then the picture of subject's right profile was taken for each subject. After the usual development and fixation of the films, the picture was enlarged to 24.8 cm × 16.8 cm for each subject. Each picture was utilized to define two standard lines for the measurement of the angle of rotation.
One of the two standard lines was called “longitudinal axis of the ear” and the other was called “line of the bridge of the nose” in this paper. The former was defined as the straight line connecting the highest point of the external ear and the lowest point of it on the enlarged picture of subject's profile. The latter was defined as the straight line connecting the highest point of the nasal bridge and the lowest point of the nasal bridge on the same picture. These two lines form the angle of rotation, which was measured by a graduator on each subject's picture.
One hundred sixty four subjects, including eighty two male subjects and eighty two female subjects in this study, ranged in a age from 19 to 22 years, with a mean of 20.9 years. Most of subjects were students in medical service and nursing schools. None of them were evaluated for aesthetic surgery.
Results : The pattern of the distribution did not differ extremely from normal bell-shaped distribution curve. Therefore, validity of arithmetic mean and standard deviation on these data was established. Then, arithmetic mean and standard deviation were calculated for three groups, namely the male group, the female group, and the total group.
For the male group, the mean and the standard deviation of the angles of rotation were 16.0° ±5.7°. For the female group, they were 14.6°±6.1°. For the total group, they were 15.3°±6.07°.
Conclusion : When reconstructive operations of the Japanese are performed, the newlydesigned external ear should be situated to show 16.0° of the angle of the rotation in male subjects or 14.6°in female subjects.
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