Hair Anatomy
Hair is located on almost every part of the body (the exceptions being palms, soles, penis, and labia). It plays an important role in appearance for both women and men and helps to transmit sensory information to the brain.
A healthy head of hair, at its peak consists of approximately 100,000 hairs - red heads and blonds have a bit more. All the hair follicles you will ever have are formed by the 22nd week in the womb, and as all of us grow older the density of the follicles decreases. There are two components to hair, the shaft and the follicle in the skin.
The shaft is composed of keratin (a hard protein) and has three layers: the medulla, the cortex and the cuticle. The medulla may or may not be present in every shaft, and the cortex is the largest component in the shaft – cells in these areas hold pigment and define your hair’s natural color. The cuticle is the outer area that most hair products attempt to impact; it has a rough composition similar to the shingles on a roof.
The follicle is similar to a sock and also contains several layers. The papilla is at the base of the follicle and sticks out a bit. It contains capillaries, and at the bottom of this papilla is the bulb. This area is the living part of the hair, and is fed by the blood in the papilla. There are also two sheaths, (an inner and outer) that protect the hair shaft. The inner sheath ends before the oil gland (sebaceous gland) and the outer sheath goes higher on the shaft. Lastly there is a muscle called the erector pili attached below the sebaceous gland on the outer sheath. When this muscle is relaxed a hair lays down, when the erector pili muscle is contracted the hair stands up.
During a hair restoration process it is important that all of these layers are removed and replanted without disruption in order to guarantee that growth continues in the newly planted hair follicle.
