Which hair layer primarily determines strength and elasticity?

• A. Cuticle
• B. Medulla
• C. Cortex
• D. Hair shaft

Answer: (C)

The cortex is where hair’s strength and elasticity come from. It’s the thick middle layer made of elongated keratin-rich cells arranged into bundles, with bonds between the protein fibers that determine how stiff or flexible the hair feels. These keratin networks, especially the disulfide and hydrogen bonds, give the cortex the ability to resist breakage while still bending and returning to its shape. The cuticle is the protective outer layer; while damage to it can weaken hair and affect porosity, it doesn’t set the inherent strength and stretch. The medulla, when present, is a soft central core that contributes little to mechanical properties. So the cortex is the key layer governing strength and elasticity.