What is the term for the outermost layer of the hair structure?

The outermost layer of the hair structure is called the cuticle. This layer is made up of thin, overlapping cells that resemble scales on a fish or shingles on a roof. The primary function of the cuticle is to protect the inner layers of the hair (the cortex and medulla) from damage, moisture loss, and various environmental factors.

Additionally, the cuticle plays a significant role in the overall appearance and texture of the hair. Healthy cuticles lie flat and protect the inner structure, giving the hair a shiny, smooth finish. When the cuticle layer is damaged or lifted, it can lead to issues such as frizziness, breakage, and dullness.

Understanding the function of the cuticle is crucial for hairstylists and cosmetologists, as it influences hair care practices, such as the choice of shampoos and conditioners that can help to maintain or restore the integrity of this protective layer.