Have you ever wondered how one little hair strand on your beautiful head is structured? Ok, you probably haven’t. But lets face it, in order for us to maintain a healthy head of hair, we have to first understand the anatomy of our hair. Like a doctor has to understand the anatomy of the human body before she makes a diagnosis; it’s equally important for natural gals (and guys) to understand the anatomy of their hair before accurately assessing her (or his) hairs’ needs. So, lets get to it! Each and every strand of hair on our heads are made up of three layers: the cuticle, the cortex, and the medulla; five chemical elements: carbon, hydrogen, oxygen, sulfur, and nitrogen; and two other things: protein (keratin) and water. Here we will be talking about the three layers that make up the hair shaft.
The cuticle is very thin and is the most outer layer of the hair shaft. It is colorless and consists of many protein cells that overlap each other. Think of this layer as the scales on a fish. The overlapping of the cells provides a strong barrier against damage to the other two deeper layers of the hair shaft (cortex & medulla). These scales act as a door-keeper by allowing moisture into the hair shaft. Because the cuticle is very thin and semi-transparent, it has the ability to reflect or refract light or in laymen terms, it has the ability to provide shine and sheen to the hair. The scales of the cuticle layer has the ability to open or close when “activated”. When the scales open, chemicals are able to freely enter the hair shaft (through the cuticle layer) and alter the protein bonds that make up the cortex layer.Unlike the other two layers, the cuticle layer is more susceptible to damage through excessive heat and manipulation.
The cortex is the second layer of the hair shaft. This layer is very thick and firm. Ironically, the cortex provides the most strength and weight to the hair shaft, however, it is more susceptible to irreversible damage. The cortex provides our hair with individual characteristics such as color, thickness, and texture (just to name a few). The hydrogen, carbon, nitrogen, oxygen, and sulfur elements introduced earlier are mainly found in this layer. Chemical hair dyes and relaxers have the most adverse affects on this layer. Because the cortex is made up of proteins, when we use chemicals to alter our hairs’ color or texture, the chemicals bombards their way through the cuticle layer and alters the bonds that make up the proteins found in the cortex layer. Did y’all hear that? I’ll say it again. The chemicals that we are accustom to using are strong enough to “activate” the cuticle (the first layer) causing it to open. The chemicals deposits color into the cortex (if it’s a hair dye) or it alters the protein bonds in the cortex (if it’s a relaxer). Once the cortex is damaged, it can not be repaired. This is why it’s sooooooo important for us naturals to avoid chemicals at all cost.
The medulla is the third most inner layer of the hair shaft. The cells that make up this layer are-like the other two layers-made up of the protein keratin. Unlike the other two layers, the medulla is not present in all hair types. It is typically found in thicker coarser hair types and is almost always absent in natural blonde hair. The medulla is also present in thick coarse beard hair. In addition, medullas are not all created equally. Some hair shafts have partial medullas while others have complete medullas. Furthermore, medullas on our head differ from the medullas on our legs, face, armpits, and any other place on our bodies that have hair. To make things even more complex, the role or function of the medulla has not been determined yet. Many scientists have provided numerous theories about the function of the medulla, but there has yet to be significant evidence as to its actual function in the hair shaft.
I find this very interesting and I might even be a little discriminatory, but this is by far my favorite layer. In the early 15th century, Africans believed that the hair was where the soul resided. Could it be that Africans unknowingly defined the role of the medulla and concluded that the medullas role was to provide a shelter for ones’ soul? After reading the facts about the medulla, we can conclude that people of African descent are more likely to have a medulla than their non-African descent counterparts. Also, because our hair is kinky and curly, I would assume that the medulla may provide a genetic blueprint for people with this hair type.