What is the primary component of the medulla in hair structure?

The primary component of the medulla in hair structure is keratin. The medulla represents the innermost layer of the hair shaft, and keratin is a fibrous protein that serves as the building block not only for hair but also for nails and the outer layer of skin. This protein provides strength and resilience to the hair, which is critical for its structural integrity.

In hairs that contain a medulla, keratin gives it the necessary properties to withstand mechanical stress. The presence of keratin is vital in determining the overall health and appearance of hair, contributing to its texture and shine. The other components mentioned—collagen, melanin, and elastin—serve different roles within the body or in other structures. Collagen contributes to skin structure, melanin is responsible for hair pigmentation, and elastin helps tissues regain their shape after stretching. These components do not primarily make up the medulla, emphasizing that keratin is the most significant constituent in this part of hair structure.