What is the name of the small, involuntary muscle at the base of the hair follicle?

The small, involuntary muscle at the base of the hair follicle is known as the arrector pili muscle. This muscle plays a significant role in the physiological response known as piloerection, which occurs when the body experiences cold temperatures or emotional responses such as fear or excitement. When the arrector pili muscle contracts, it causes the hair to stand upright, creating the appearance of "goosebumps."

Understanding the structure and function of the arrector pili muscle is important in the study of hair growth and skin physiology. In contrast, dermal papillae are small, nipple-like projections located at the base of the hair follicle that provide nutrients to the hair. The sebaceous gland is responsible for producing oil to lubricate the hair and skin, while the epidermal layer refers to the outermost layer of skin, which does not directly relate to the involuntary muscle associated with hair follicles. Recognizing the specific roles of these components allows for a deeper understanding of hair and skin health in cosmetology.