Getting to Know Your Hair: The Hair Shaft

After treating the many different forms of hair loss in both men and women for more than forty years, the experts at The Griffin Center of Hair Restoration and Research have developed a keen appreciation for the anatomy of hair.  Although most people don’t give it too much thought, each individual hair is actually an extremely complex structure made up of two main components: the follicle and the hair shaft.  In last month’s Getting to Know Your Hair blog, we described the various specialized organs deep inside the hair follicle that make hair growth possible.  This month, we will delve into the hair shaft itself, the portion of the hair that can be seen above the skin’s surface.

Getting to Know Your Hair The Hair Shaft

Because the hair growth process begins inside the hair follicle, the only “living” portion of the hair is found under the skin.  As newly formed cells push the older cells upward, each hair cell undergoes a process called keratinization, gradually losing its nucleus and filling with fibrous proteins.  By the time the hair cells reach the surface of the scalp, they exhibit no biochemical activity, making them functionally “dead” even though the hair follicle itself is still alive and active.  A cross section of this resulting hair shaft may be divided roughly into three layers: the medulla, the cortex, and the cuticle.

  • Medulla: This disorganized, open area at the very heart of the hair fiber is the most soft and fragile, and is not unlike the marrow that is in the center of bones. Scientists are still uncertain about what exact purpose the medulla might serve, and some hairs are missing this layer entirely.  However it does appear to be more prominent in hair that has turned grey or white due to advancing age.
  • Cortex: Acting as a middle boundary between the medulla and the cuticle, the cortex is the thickest layer of the hair shaft and contains the pigment melanin, which gives hair its color. The shape of the cortex determines how straight or curly the hair is, with round fibers producing straight hair and oval fibers producing hair that is more wavy or curly.
  • Cuticle: The outermost layer of the hair shaft is formed entirely of dead cells that overlap like the scales of a fish, shifting as the hair flexes, giving the hair shaft strength, and protecting the more delicate layers underneath. The cuticle is also coated with a single molecular layer of lipid that allows the hair to repel water.  Damaging hair care practices can strip the cuticle, allowing the hair to dry out and become brittle.

At The Griffin Center we study all aspects of hair, both inside and out, and so we know that the complexity of the hair follicle can sometimes make diagnosing the underlying cause of hair loss difficult.  That is why our hair restoration experts, Dr. Edmond Griffin and Dr. Ashley Curtis, insist that every case of hair loss requires a thorough examination and an individual diagnosis.  If you are concerned about your own hair loss, or are interested in learning more about the many surgical and non-surgical hair restoration options that are available, follow us on Facebook, Twitter, and Google+ to get the latest news or answers to your questions about hair restoration or contact The Griffin Center of Hair Restoration so that we can schedule an appointment for a full hair loss consultation.