A small muscle which contracts and makes the hair on the skin stand up when someone is cold or afraid.
Muscles attached to hair follicles that cause “goose bumps” when involuntarily contracted.
The tiny muscles that encircle hair follicles and, when activated, make the hair stand upright. These muscles are responsible for phenomena like “hair standing on end” and “goosebumps.” They are also known as erector pili muscles.