Let’s understand Anatomy of the hair follicle through Anatomy Hair Chart
A hair follicle is an absorbing structure that can be divided into 3 parts or segments; lower, middle and upper. The lower segment is known as bulb and suprabulb, the middle segment is known as isthmus, and the upper segment is known as infundibulum. The lower segment; bulb or superbulb, extends from the bottom of the follicle to the inclusion of the erector pili muscle or the arrector pili muscle.
The middle or central segment is a comparatively short section that extends from the insertion of the erector pili muscle to the doorway of the sebaceous gland duct. The upper part extends from the access of the sebaceous gland duct to the follicular orifice.
With time to time, the attributes and features of the hair follicle change continuously and considerably during the complete hair growth cycle, thus making follicular anatomy even a more complex structure to understand.
The extent of human hair follicles differs considerably during the continuation of the follicles. Anagen hair contrasts in size from large terminal hairs, like those on the scalp, to the diminutive vellus hairs that cover up almost the entire glabrous skin apart from palms and soles. Under such hormonal influences, the vellus hair follicles in the male beard area typically thicken and darken at puberty.
The human hair follicular life cycle can be separated into 3 phases: anagen, catagen, and telogen. The anagen phase that includes active growth whereas the second phase; catagen marks follicular regression, and the last one; telogen phase represents a resting period. In the human scalp, the anagen phase goes approximately 3-4 years in hair follicle growth, while the catagen phase goes about 2-3 weeks, and the telogen phase lasts about 3 months.