Idaho Cosmetology Licensure Practice Exam

The cuticle layer of the hair plays a crucial role in protecting the inner layers of the hair shaft, which include the cortex and the medulla. This outermost layer consists of transparent, overlapping cells that act like shingles on a roof, creating a barrier against environmental damage, mechanical wear, and moisture loss. By maintaining this protective shield, the cuticle helps to keep the hair healthy and intact, preventing issues such as breakage and split ends.

While other layers of the hair serve different functions—such as pigmentation in the cortex or nutrient supply from the scalp—the cuticle's primary function remains its role in protective defense. This understanding reinforces the importance of caring for the cuticle, as damage to this layer can lead to weakening of the hair structure and detrimental health of the hair overall.