Which part of the hair shaft is the outermost protective layer?

• A. Medulla is the outermost layer.
• B. Cortex is the outermost layer.
• C. Cuticle is the outermost layer.
• D. There is no outer layer.

Answer: (C)

The outermost protective layer of the hair shaft is the cuticle. It’s made of flat, scale-like cells that overlap like shingles, forming a protective cap around the inner layers. Beneath the cuticle lies the cortex, which provides the hair’s strength, elasticity, and color, and at the center is the medulla, which may be absent in finer hair. Because the cuticle covers and seals the inner structures, it plays a key role in moisture retention and how the hair interacts with chemical services. When the cuticle is smooth and intact, the hair looks shiny and behaves predictably; when it’s damaged or raised, the hair becomes more porous, absorbs treatments unevenly, and can appear dull or frizzy.