Which part of the hair shaft is involved with the cuticle, cortex, and medulla?

The hair shaft is the visible part of the hair that extends above the scalp, and it is made up of three primary layers: the cuticle, cortex, and medulla. The cuticle is the outermost layer, consisting of flat, scale-like cells that protect the inner structures. Beneath the cuticle lies the cortex, which forms the bulk of the hair and is responsible for its strength and elasticity due to the presence of keratin fibers. The innermost layer, the medulla, is present in some types of hair and may contribute to its overall structure and characteristics.

Understanding the specific roles of these layers is essential in cosmetology, as they impact hair care, treatment decisions, and styling options. The relationship between these components is critical for maintaining the health and appearance of hair. In contrast, the root refers to the part of the hair that is embedded in the follicle. The follicle itself is a structure in the skin from which the hair grows but does not include the layers mentioned. The bulb is the rounded part at the base of the follicle, where cell division occurs to produce new hair. Only the shaft encapsulates the cuticle, cortex, and medulla, confirming that this is the correct answer.