Which hair structure is the outermost layer that protects the hair?

The outermost layer of the hair, responsible for protecting the inner structures, is the cuticle. The cuticle consists of overlapping, scale-like cells that lie flat against the hair shaft, creating a barrier that safeguards the underlying layers from physical and environmental damage. It plays a crucial role in maintaining the integrity of the hair, helping to prevent moisture loss and shield the hair from the sun, pollutants, and chemical processes.

In contrast, the cortex is located beneath the cuticle and contains the fibrous proteins and melanin responsible for the hair's strength, color, and elasticity. The medulla, if present, is the innermost layer and has a less defined role, mainly contributing to the overall structure of the hair. The root refers to the part of the hair that is contained in the follicle beneath the scalp's surface, and it is integral to hair growth rather than protection. Thus, the cuticle is essential for protecting hair health and ensuring it appears shiny and healthy.