1. 在耳轮内缘上，设耳轮脚切迹至对耳轮下脚间中、上1/3交界处为A点(图1)。

2. 在耳甲内，由耳轮脚消失处向后做一水平线与对耳轮耳甲缘相交，设交点为D点(图1)。

3. 设耳轮脚消失处至D点这线的中、后1/3交界处为B点(图1)。

4. 设外耳道口后缘上1/4与下3/4交界处为C点(图1)。

5. 从A点向B点做一条与对耳轮耳甲艇缘弧度大体相仿的曲线(图1)。

6. 从B点向C点做一条与耳轮脚下缘弧度大体相仿的曲线(图1)。

7. 从B点向D点做一连线为BD线(图1)。

1. At the inner border of the helix, set point A where it is 1/3 of the distance from helix crus notch to the inferior crus of antihelix (Fig. 1).

2. Inside the concha, draw a straight line back from where helix crus ends to intersect with antiheli and concha, set this as point D (Fig.1).

3. Set point B at 2/3 of the distance from where the helix crus ends to point D (Fig. 1).

4. Set point C at 1/4 of the distance from the apex of the posterior border of the external ear canal (Fig. 1).

5. From point A to point B, draw a line curved along the helix and cymba conchae (Fig. 1).

6. From point B to point C, draw a line curved along helix crus (Fig.1).

7. Connect a line from point B to point D as the BD line (Fig. 1).

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