Hair structure

The hair follicle is located in the dermis. The dermal papilla is at the base of the hair follicle. The papilla is fed by the bloodstream, which carries nourishment to produce new hair – it is the point from which hair grows. The hair follicle consists of:

• the hair bulb
• the inner root sheath
• the hair shaft

New hair is made inside the onion-shaped hair bulb that lies within the hair follicle. It has a cavity in which the dermal papilla is embedded. New cells are continuously produced in the lower part of the bulb. As they grow and develop they steadily push the previously formed cells upwards. Special cells in the hair bulb produce the pigment that colors hair. The pigment is called melanin.

The sebaceous gland is situated in the upper follicle, as is the erector muscle of the hair.

The bulb contains the hair matrix, the germ layer that forms the inner root sheath, and the hair shaft that is composed of three layers: medulla, cortex and cuticle. Medulla is the innermost layer. The middle layer – cortex – accounts for the greatest portion of the hair shaft, and contains fibers which are important for hair‘s strength and elasticity. The outermost layer is known as the cuticle. The cuticle is thin and colorless and serves to protect the cortex.

The outer root sheath surrounds the hair follicle and secures the hair shaft within the follicle.