Which hair layer contributes most to the hair's weight?

• A. Cortex
• B. Medulla
• C. Hair shaft
• D. Cuticle

Answer: (D)

The layer that contributes most to the hair’s weight is the cortex. This middle layer forms the bulk of the hair’s mass and contains the dense keratin fibers that give hair its strength, structure, and color. Because of its substantial keratin content, the cortex adds far more weight than the other layers. The cuticle sits on the outside as a very thin protective veil of overlapping cells, so it adds only a small amount of weight but greatly influences surface texture and shine. The medulla, when present, is often hollow or loosely packed, contributing little to overall mass. So, the heaviest, most mass-bearing part of the hair is the cortex.