She has become a bundle of nerves, starting at the slightest sound.

她成了神经过敏的人， 听见一点点声响就惊恐不安。

《新英汉大辞典》

He is a bundle of nerves.

他是个神经极度紧张的人。

youdao

He confessed to having been a bundle of nerves.

他承认自己一直神经极度紧张。

youdao

But to reach the physiological root of those sensations, we need to take a close look at the vagus nerve -- actually a bundle of nerves that starts at the base of the brain and branches out through the body, linking up with the facial and vocal muscles and the heart, lungs, and gut.

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