The main component of the hair shaft is:

• A. Dermis
• B. Cortex
• C. Medulla
• D. Cuticle

Answer: (B)

The cortex is the main component of the hair shaft. It forms the thick middle layer that carries most of the hair’s mass, made up of keratin fibers and pigment melanin. This combination gives hair its strength, elasticity, and color, so the cortex largely determines how the hair feels and looks. The medulla sits at the center and may be absent in finer hair, so it isn’t the primary structure in most strands. The cuticle is the outer protective layer of flat cells; it shields the cortex and affects surface smoothness and shine but does not provide the main structural or color properties. The dermis is a skin layer beneath the epidermis and is not part of the hair shaft itself.