pl. arrectores pilorum [ä·rek′tor pī′lī]
Etymology: L, raisers of the hair
minute smooth muscles of the skin, attached to the connective tissue sheath of the hair follicles; when they contract they cause the hair to stand erect, producing the appearance called goose flesh.
arrector pili(ă-rek′tŏr pī′lī″, pil′ē) (ar″ek′tōr′ēz pī″lōr′ŭm, pil-ōr′) plural.arrectores pilorum [L. arrector, raiser + pilus]
One of the involuntary muscle fibers arising in the skin and extending down to connect with the hair follicles on the side toward which the hair slopes. After certain stimuli, including cold or fright, the muscle fibers contract, straighten the follicles, and raise the hairs, resulting in piloerection.