What are the three layers of hair, starting from the innermost to outermost layer?

The three layers of hair, starting from the innermost to the outermost layer, are indeed the medulla, cortex, and cuticle.

The medulla is the central core of the hair strand. It is not present in all hair types but, when it is, serves as a supporting structure. Surrounding the medulla is the cortex, which is the thickest part of the hair and contains fibrous proteins and melanin, contributing to the hair's strength, color, and texture. Finally, the cuticle is the outermost layer, composed of overlapping, scale-like cells that protect the inner layers from damage and dehydration.

This layered structure is crucial for understanding hair growth, treatment, and damage repair, which are important concepts in the fields of electrolysis and laser treatment for hair removal and skin care. The correct progression of these layers highlights the significance of each part in terms of aesthetics and hair maintenance practices.