The Hair Loss Encyclopedia
small muscle causing hair to stand up, creating goosebumps
The arrector pili muscle is a small, smooth muscle attached to the base of a hair follicle. When it contracts, usually in response to cold or emotional stimuli, it causes the hair to stand up, a phenomenon known as "goosebumps." This muscle plays a role in thermoregulation and can also be involved in the body's response to stress.