Anatomy of Black Hair

"There are two characteristic presentations of black hair: black hair in its natural state and chemically-straightened black hair."

The structure of the hair is made of two main parts- three for some people. The outer layer, called the cuticle, consists of 5-11 overlapping scales of cells that protect the cortex underneath. The cortex comprises 80-90% of the hair fiber and consists of chains of proteins that coil to form the hair fiber's structure. These protein chains also gives hair its strength and elasticity. The cortex is also where melanin (which denotes your natural hair colour) can be found. The medulla is found only in thick, course hair. It has no significance, except to make the hair thicker. When your hair becomes damaged the scales of the cuticle can stand out or break off, exposing the cortex and making your hair feel dryer and harder to brush.

While the basic structure of hair is the same for everyone, there are differences in hair texture by race and gender. And obviously, chemically altered hair differs from hair in its natural state across race and gender. This page will discuss the anatomy of black hair- both in its natural and relaxed states.

 

Black Hair in its Natural State

In its natural state, black hair curls, twists, bends and kinks in various angles along the hair fiber. These characteristics are decided by the shape of the hair follicles. Kinky hair fibers are produced from oval-shaped follicles while straight hair grows from larger, round follicles.

Think of our oval follicles as the scissors used to curl a ribbon. The angle of the follicles nick our strands causing them to curl.

The oval shape of our follicles is also the reason that black hair is more fragile than other hair types. Because of the nicking of hair strands caused by our oval-shaped follicles, the shape and diameter of black hair does not remain constant along the fiber. The diameter of black hair decreases and the hair flattens around the hair bends (where the follicle nicks the hair strands creating a curly texture). These thinner points along the hair length are fragile and prone to breakage.

Chemically-Straightened Black Hair

The thinning of the hair fiber at the points where the hair bends (where hair is nicked by the follicles) are present even after hair is straightened. As a result, straightened black hair is just as fragile as black hair in its natural state. Relaxed black hair is another story... Remember the post about hair bonds? Let's revisit the part about disulfate bonds:

As we know, hair is made up of protein chains held together by a series of physical and chemical bonds, which give hair its shape and strength. Disulfate bonds join the sulfur atoms of 2 nearby cysteine amino acid chains. Therefore, the more disulfate bonds, the kinkier and curlier the hair. These bonds can't be broken by water or heat, but they can be permanently broken by chemical agents. Disulfate bonds are the key factors in supplying the hair its' strength and durability.

Relaxers work to disrupt these bonds and, again, once these bonds are broken they cannot be reformed (which is why we have to do a BC or cut off all our relaxed hair for our hair to return to its natural state). So, relaxed black hair is weaker than black hair in its natural state because in addition to the thin spots along each hair strand at the strand's bends (due to the nicking of the follicles), the disulfate bonds in relaxed black hair are broken, which presents further threats to hair's strength and durability.