Which layer of hair lies in between the cuticle and the medula?

The correct answer is the cortex, as it is the layer of the hair that lies between the cuticle and the medulla. The cuticle is the outermost layer of the hair, consisting of overlapping scale-like cells that protect the inner layers. Beneath the cuticle, the cortex makes up the bulk of the hair structure and contains fibrous proteins and melanocytes, which are responsible for hair's strength, elasticity, and pigmentation. The cortex's composition plays a crucial role in how hair behaves when subjected to chemical treatments, coloring, and styling.

The medulla is the innermost layer of hair that may not be present in all hair types but is involved in the hair’s structure and integrity. Understanding the layering of the hair is essential for hair color specialists, as each layer interacts with hair treatments differently. Knowledge of these layers is fundamental for making informed decisions regarding hair care and treatments.