What portion of the hair projects above the epidermis?

The hair shaft is the part of the hair that extends above the surface of the epidermis, making it the visible portion of the hair. This part is composed of dead, keratinized cells, which provide texture and structure. The hair shaft begins at the base of the hair follicle beneath the skin and continues outward, where it can be styled, cut, or colored.

In contrast, the hair root is the portion of the hair that is embedded within the scalp or skin, secured in the hair follicle. The dermal papilla is a small structure at the base of the hair follicle that contains blood vessels and nerve endings, playing a crucial role in providing nutrients to the hair. The hair follicle itself is the structure that surrounds the root of the hair, anchoring it within the skin. Each of these components is critical for hair growth and health, but only the hair shaft is the part that is external and visible.