What is the function of the hair cuticle?

The hair cuticle serves an essential protective function for the hair. This outermost layer consists of overlapping, scale-like cells that help to shield the inner structures of the hair, including the cortex and medulla, from environmental damage and mechanical stress. By providing this protective barrier, the cuticle helps maintain the integrity of the hair, minimizing issues such as split ends, breakage, and overall damage due to factors like heat styling, UV exposure, and chemical treatments.

While the cuticle does play a role in the appearance of hair, such as contributing to shine, its primary function is protection. The options regarding color and moisture absorption refer to different properties and behaviors of hair fibers that do not pertain to the cuticle's core purpose. The cuticle itself does not add color or directly absorb moisture, though a healthy cuticle can enhance the hair's shine and manage its moisture retention indirectly.