American Academy of Professional Coders (AAPC) Practice Exam

What are the three layers of the hair shaft composed of keratin?

1. Medulla, cortex, cuticle

2. Medulla, bulb, shaft

3. Cortex, cuticle, root

4. Root, shaft, layer

The correct answer is: Medulla, cortex, cuticle

The hair shaft consists of three primary layers, which are the medulla, cortex, and cuticle. The medulla is the innermost layer and may be absent in finer hair types. It consists of loose cells and air spaces, contributing to overall hair structure. The cortex forms the middle layer, which is thick and made up of elongated cells. This layer is responsible for the strength, texture, and color of the hair due to the presence of keratin and melanin. The cuticle is the outermost layer, composed of overlapping, scale-like cells that protect the inner layers from damage and moisture loss. This structure provides hair with its shine and overall health. Other options do not accurately represent the layers of the hair shaft. The second choice includes the bulb and shaft, which do not refer to the structural layers of the hair itself. The third option lists the root and cuticle; however, the root is not a layer of the hair shaft, and it does not include the cortex. Lastly, the fourth choice mentions the root and layer, but the term "layer" is too vague and non-specific to accurately describe the composition of the hair shaft. Thus, the correct identification of hair shaft layers as medulla, cortex,