Milady Cosmetology Practice Exam

The three main layers of the hair shaft are indeed the cuticle, cortex, and medulla.

The cuticle is the outermost layer of the hair, consisting of transparent, scale-like cells that overlap like shingles on a roof. Its primary function is to protect the inner layers of hair from damage and environmental factors.

The cortex, located beneath the cuticle, is the thickest layer of the hair and contains fibrous proteins and melanin, which contributes to the hair's strength, elasticity, and color. This layer is responsible for the overall structure and characteristics of the hair.

The medulla is the innermost layer of some hair types, which may be fully intact or absent in finer hair. The presence or absence of this layer can help determine the hair's texture and density.

In contrast, the other options mention layers that are not part of the hair shaft itself, such as the epidermis and dermis, which are part of the skin, or sebum, which is an oily substance produced by sebaceous glands that lubricates hair and skin but does not comprise a layer of the hair shaft. Therefore, the correct answer highlights the specific structure of the hair, focusing on the parts that directly make up the hair shaft.