3 adjectives to describe archings

Now, I had done this thing with a wondrous quickness; so that I was under the mighty arching of the legs before the Yellow Thing did wot of my intent.

It was telegraphed to him by the twitching and vibration of great muscles, by the stiff arching of the neck, and the snorting breathing.

" She gave me her hand, and I would have knelt had she not prevented me by a surprised arching of her eyebrows.

3 adjectives to describe  archings