Then there's flexion, where the fetal chin presses against its chest as its head meets resistance from the pelvic floor.

接着是俯屈，胎儿的颏贴近胸壁，因为他的头遇到盆底肌的阻力。

Simply put it means to lift through the entire range a joint can safely articulate between full extension and full flexion.

简单地说，就是举起哑铃后，关节可以安全地活动的全部范围，从完全伸展到完全曲起。

Nor does this—its amazing strength, at all tend to cripple the graceful flexion of its motions; where infantileness of ease undulates through a Titanism of power.

这种惊人的力量，一点也不会削弱它运动时那种优雅的曲线美，婴儿般的轻松通过巨人般的力量波动起伏地表现出来。

Then, we also have an electrical motor over here that controls this transmission that you can see that controls flexion and extension of the elbow.

之后，我们这里还有一个电机，它控制这个传输，你可以看到它控制肘部的弯曲和伸展。

The isometric was an elbow flexion, aka a bicep curl, at maximal contraction held for 3 seconds 10 times at a 20-degree flexion.

精力训练是做肘部屈曲，也就是二头肌弯曲，以极限收缩保持3秒，以20度屈曲10次。

If that bending motion decreases the angle of the joint and brings those bones together, like when I bend my arm together, that movement is called flexion.

如果弯曲运动减少关节的角度，使骨骼结合在一起，就像我弯曲手臂一样，这种运动称为屈曲。

Cephalic, or head-first, is the first type, and furthermore the most common and optimal presentation for easy delivery is a type of cephalic presentation called vertex, which includes complete flexion of the head as well.

头先露，第一种类型；进一步说，对于顺产来说最常见的、最佳的先露，是一种称为顶先露的头先露，包括完整的头部俯屈。

Think like the bicep curl where you want to start at the very bottom, elbows straight and at full extension, and then lift all the way to the top, elbow bent and at full flexion.

想象一下二头肌弯曲的样子，从最下面开始，肘部伸直是完全伸展，然后一直抬起，肘部弯曲就是完全弯曲。

Such is the subtle elasticity of the organ I treat of, that whether wielded in sport, or in earnest, or in anger, whatever be the mood it be in, its flexions are invariably marked by exceeding grace.

这就是我所涉及的这个器官的微妙的灵活性，无论是在嬉戏，还是一本正经，还是在发脾气，无论处于怎样的情绪，它在弯曲活动的时候总是带有超凡的优雅。