In hair anatomy, which part is responsible for the strength and elasticity of the hair?

The cortex is the part of the hair that plays a crucial role in providing strength and elasticity. It makes up the majority of the hair's structure and is composed of long chains of keratin proteins. This inner layer not only contributes to the hair's strength but also gives it its texture and color due to the presence of melanin. The cortex contains cells that are filled with fibrous proteins, which allow it to withstand various types of stress and tension without breaking.

The cuticle, while important for protecting the hair and contributing to its shine, does not provide the inherent strength and elasticity. The medulla, found in the center of the hair shaft, is often absent in finer hair and is not responsible for the overall strength of the structure. The term "outer layer" does not specifically refer to a specific anatomical part of the hair, which further clarifies why the cortex stands out as the primary contributor to strength and elasticity in hair anatomy.