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Understanding the Anatomy of Hair


Understanding the anatomy of hair is essential for understanding the process of hair growth. While hair color and texture may vary, the actual anatomy of our hair is essentially the same from person to person. Keep reading to learn about hair anatomy and find out how you can make your hair instantly look thicker without waiting for it to grow.

Breaking Down Hair Anatomy

The human body is covered in hair. Most of these hairs are vellus hairs, which are fine, short and colorless. But certain areas like the scalp, eyelashes and eyebrows have thicker, darker hairs called terminal hairs.

Each hair is made up of two parts: the hair shaft, which is the visible part of the structure; and the hair follicle in the scalp, which produces and grows the hair shaft.

The Hair Shaft

The hair shaft is the part of the hair anatomy that you can see on the surface of your skin. The hair shaft is primarily made up of a protein called keratin. Keratin, which is formed from the breakdown of amino acids in the proteins we eat, is also an important component of our skin and nails. This part of the hair structure is non-living, which is why haircuts don’t hurt!

The hair shaft has three parts:

Medulla – a honeycomb-like core made of sugars and amino acids
Cortex – a hard keratin layer that surrounds the medulla
Cuticle – the protective outer layer made up of overlapping keratin scales

The cortex and cuticle contain a pigment called melanin, which determines the color of your hair.

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The Hair Follicle

Otherwise known as the hair root, the hair follicle is the living part of the hair located beneath the surface of the skin. Humans have almost five million hair follicles, 80,000 to 100,000 of which are located on our scalp.  The hair follicle is the growth structure that produces the hair, and it also anchors the hair shaft in the skin.

The hair follicle is made up of four parts:

Hair Bulb

The hair bulb is located at the base of the hair follicle. This is where cells divide to form the hair shaft in a continuous cycle of growth and rest, otherwise known as the hair growth cycle (more on that below).

The hair bulb’s anatomy is made up of the dermal papilla and the matrix. The dermal papilla, located at the base of the hair bulb, contains a vascular network that nourishes the hair bulb with nutrients. Through this blood supply, the dermal papilla also receives hormonal signals that help regulate hair growth. The matrix contains melanocytes, a type of skin cell that produces the pigment that determines your hair color (the color of the hair shaft).

Sebaceous Gland

The sebaceous gland produces an oily substance called sebum that moisturizes both the hair shaft and the skin.

The Inner and Outer Root Sheath

These protein structures contain and protect the hair follicle.

Arrector Pili Muscle

The arrector pili is a small muscle attached to the hair follicle. When the arrector pili muscle contracts, it literally causes the hair to stand on end. This is what causes goosebumps.

How the Hair Anatomy Can Affect Hair Growth

Here are examples of how two parts of the hair anatomy, the hair shaft and the dermal papilla, can affect hair length and hair growth:

  • Damage to the hair shaft can cause breakage, limiting hair length, which can make it seem like hair growth has slowed down. Following healthy hair care habits like reducing heat styling, chemical straightening treatments and bleaching can help minimize breakage and damage.
  • If the dermal papilla doesn’t receive proper nutrients from the blood supply, the hair bulb will be less able to efficiently manufacture new hair cells. That’s why eating a healthy, balanced diet is so important for hair growth.
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How to Get Thicker-Looking Hair Now

If you’re looking to boost your confidence and make fine, thin hair look thicker while you wait for new hair growth, Toppik Hair Building Fibers can help. Toppik Hair Fibers are made from keratin, the same protein as in human hair. So they add the look of thickness are are virtually undetectable. Just shake or spray Toppik Fibers into areas where you would like to see extra thickness, and lock the fibers in place with Toppik FiberHold Spray. Toppik Fibers are an instant solution to make fine or thin hair look great!

Do you have questions about hair anatomy and how hair grows? Ask us in the comments section below.

Colleen Welsch is a freelance beauty writer and blogger specializing in hair care, hair growth education and beauty.

2 Responses

    1. Toppik is a cosmetic product that makes hair look thicker, but washes out easily with shampoo. If you follow the directions for topical use, it shouldn’t cause side effects like these. Thank you

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