The cuticle of a hair is the outermost layer of the hair (see the diagram below).
To appreciate this in the overall context of the structure of hair, note that, structurally, hairs are threads of fused (i.e. attached together), dead, keratinized cells. They consist of two main parts:
- The hair shaft is the visible part of the hair that protrudes through the skin. It is composed of three layers. The innermost layer is called the medulla and is only present in large thick hairs. The middle layer is called the cortex and outermost layer is called the cuticle.
- The hair root is the part of the hair below the surface of the skin that includes and interacts with many other associated structures within the dermis and hypodermis layers of skin.
More about the cuticle of hairs:
The cuticle of a hair extends along its length, i.e. through the hair root as well as the hair shaft. The cuticle of a hair is a thin colourless layer that protects the cortex of the hair.
The hair cuticle is just one of many structures of or associated with hair follices. For more information see the labelled diagram of a hair follicle. See also notes about other accessory structures of the skin.
The topic of the structure of a hair follicle is included in some courses in health sciences, including subjects such as nursing, skin care, hair care, beauty therapy and various holistic therapies.