What layer of the hair provides strength and elasticity?

The cortex is the layer of the hair that plays a crucial role in providing strength and elasticity. Composed primarily of long chains of keratin proteins, the cortex is the thickest layer and makes up the majority of the hair's structure. Its unique structure allows it to absorb moisture and maintain flexibility, which is essential for the hair to withstand styling and environmental factors without breaking.

In contrast, the cuticle serves as the outer protective layer of the hair, helping to prevent damage from external elements but does not contribute to the hair's internal strength and elasticity. The medulla, the innermost layer of the hair, is present in only some hair types and is not essential for the overall strength and elasticity. The follicle is the structure from which hair grows, providing nourishment, but it does not impact the physical properties of the hair strand itself.