Which structure is the innermost layer found in coarse hair and beard hair, and is absent in fine hair?

Which structure is the innermost layer found in coarse hair and beard hair, and is absent in fine hair?

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

Answer: (A)

The innermost layer of the hair shaft is the medulla. In coarse hair and beard hair, the medulla is typically well-developed, forming a distinct central core. In fine hair, the medulla is often absent or greatly reduced, so the shaft lacks that inner core. The cortex lies outside the medulla and provides strength and color, while the cuticle is the outer protective layer. The follicle is the hair’s root structure within the skin, not a layer of the shaft. That’s why the medulla fits the description.

The innermost layer of the hair shaft is the medulla. In coarse hair and beard hair, the medulla is typically well-developed, forming a distinct central core. In fine hair, the medulla is often absent or greatly reduced, so the shaft lacks that inner core. The cortex lies outside the medulla and provides strength and color, while the cuticle is the outer protective layer. The follicle is the hair’s root structure within the skin, not a layer of the shaft. That’s why the medulla fits the description.