What is the role of the cuticle in hair?

The cuticle plays a vital role in the structure and health of hair by serving as the outermost protective layer of the hair shaft. It is composed of overlapping, scale-like cells that form a barrier against environmental damage, preventing moisture loss and shielding the inner layers, which include the cortex and medulla. This protective function is essential for maintaining the overall integrity of the hair, as damage to the cuticle can lead to frizz, breakage, and loss of luster.

In contrast, while strength is important in hair, it primarily derives from the cortex rather than the cuticle. The cuticle itself is thin and fragile, mainly focusing on protection. Although melanin in the hair's cortex is responsible for its color, the cuticle does not contribute to pigmentation. Lastly, the nourishment of hair follicles comes from blood supply and not from the cuticle layer, making its primary function protection of the inner structures. Thus, the cuticle's main role is to protect and preserve the integrity of the inner layers of the hair shaft.