pili

Arrector Pili are tiny muscles attached to the base of the hair follicles.

竖毛肌（立毛肌）是一些附着在毛底部的细小的肌肉。

Arrector Pil : Each hair follicle has a tiny muscle called the arrector pili attached to it.

立毛肌：每一个发下面连着一个很小的肌肉叫做立毛肌。