What is the outermost layer of the hair shaft?

The outermost layer of the hair shaft is known as the cuticle. The cuticle consists of overlapping, scale-like cells that protect the inner layers of the hair, specifically the cortex and medulla. This protective layer plays a crucial role in maintaining the hair's integrity, preventing damage and moisture loss. The cuticle also contributes to the overall appearance of the hair, as it reflects light and helps the hair achieve a shiny appearance.

Understanding the structure of hair is essential for estheticians, as it influences hair treatments and product choices. The cortex, which is found beneath the cuticle, contains the hair's pigment and adds strength. The medulla, which is the innermost layer, is not present in all hair types and plays a lesser role in hair health and appearance. The follicle, although crucial for hair growth, is not a part of the hair shaft itself but rather the structure that surrounds the root of the hair.