The tough exterior layer of the hair structure is called the

• A. Cuticle
• B. Cortex
• C. Medulla
• D. Fibril

Answer: (A)

The tough exterior layer is the cuticle. Hair has three main layers: the outermost cuticle, the middle cortex, and the central medulla. The cuticle is made of flat, scale-like cells that overlap like shingles, forming a protective shield for the inner cortex and medulla. When these scales lie flat and intact, hair looks smooth, shiny, and resists damage. If the cuticle is damaged or lifted, the hair surface becomes rough and dull because the protective barrier is compromised, allowing moisture and chemicals to penetrate more easily. The cortex provides strength and color, while the medulla is the central core in thicker hairs, not always present. Fibril isn’t a standard term for a hair layer.