PSI Barbering Practice Exam 2026 – All-in-One Resource to Master Your Certification!

The outermost layer of the hair is known as the cuticle. This layer consists of overlapping, scale-like cells that protect the inner structures of the hair. The cuticle plays a crucial role in maintaining the hair's integrity by shielding it from environmental damage, such as heat and chemical exposure, which can lead to dryness and breakage.

The cortex is situated beneath the cuticle and is responsible for the hair's strength and elasticity, making it essential for the hair's overall structural integrity. The medulla is the innermost layer, often absent in fine or thin hair, and it contributes less to the hair's properties. The hair shaft refers to the entire visible part of the hair that extends outside the scalp but does not specify the individual layers.

Understanding the function and structure of the cuticle can help in choosing appropriate hair care products and treatments that maintain healthy hair.