The hair shaft is the part of your hair that can be seen above your scalp. It is made of a protein called keratin, compacted and fused together. Keratin is the same material that nails, hoofs, feathers, and claws are composed of. Keratin is a remarkably strong protein, very resistant to wear and tear.
Each hair root is connected to a smooth muscle called the arrector pili that contracts in response to nerve signals from the sympathetic nervous system, making the external hair shaft “stand up.”
The hair shaft is the part of the hair that is above the skin.
A normal hair shaft grows in 3 phase structure-Anagen, Catagen and telogen. It starts from anagen and ends with Catagen. This cycle is life-long and never stops. If any of the three phases is disturbed due to any of the above mentioned causes, then hair loss or hair loss related ailments are encountered.