arrector pili muscles

bundles of smooth muscle fibers, attached to the deep part of the hair follicles, passing outward alongside the sebaceous glands to the papillary layer of the corium; they act to pull the hairs erect, causing “goose bumps” or “goose flesh” (cutis anserina). Syn: musculi arrectores pilorum [NA], arrectores pilorum, erector muscles of hairs.