Mechanical hair loss, also known as traction alopecia, alopecia hair alopecia, pressure, are caused by exogenous damage the scalp hair loss. When beauty women hair, long and tight hair, strong hair and use hairpins, often wrapped around the hair too long, habitual, Cap is too tight or to maintain certain hairstyles and hair for long strained, resulting in chronic hair pulling. Long-term tension lead to clogged hair follicle dermal papilla of the capillaries, local hair follicles decrease hairs in telogen. Some special hair cause hair to break or fall off, hair damaged by various chemicals, and may fracture under the action of pulling, such as Beijing opera actors and athletes, for performances and competitions, often wears her hair pulled back and a Ribbon or rubber band tightly tied up, cause the forehead hair breaking off, hairline receding. Hair loss occurs in the hair by pulling part, severe nipple damage or pull the hair follicle, hair can't regenerate, cause permanent hair loss. Trichotillomania is the patient conscious or unconscious hair, eyebrows, beards, armpit or pubic hair removed. General is uprooted. If the hair is not all out and a predisposition to hair loss so that broken is broken. Hair in catagen. Women edge hair folliculitis of the scalp is a common cause of traction alopecia.