Which of the following is a structure found within the hair bulb?

• A. Hair papilla
• B. Epidermal ridge
• C. Arrector pili muscle
• D. Sebaceous gland

Answer: (A)

Verified step by step guidance

1. Step 1: Begin by understanding the anatomy of the hair bulb. The hair bulb is the base of the hair follicle, located in the dermis, and is responsible for hair growth. It contains several structures that support this function.
2. Step 2: Identify the role of the hair papilla. The hair papilla is a structure found within the hair bulb. It contains blood vessels that supply nutrients and oxygen to the growing hair cells, making it essential for hair growth.
3. Step 3: Examine the other options provided. The epidermal ridge is part of the skin's surface and not located within the hair bulb. The arrector pili muscle is attached to the hair follicle but is external to the bulb. The sebaceous gland is also associated with the hair follicle but is not part of the hair bulb itself.
4. Step 4: Compare the anatomical location and function of each option to determine which structure is specifically found within the hair bulb. The hair papilla is the only structure listed that resides within the bulb and directly contributes to hair growth.
5. Step 5: Conclude that the correct answer is 'Hair papilla,' as it is the structure found within the hair bulb, while the other options are external or unrelated to the bulb.