American Academy of Professional Coders (AAPC) Practice Exam

Which layer is known as the deepest of the five layers of the epidermis?

1. Stratum Spinosum

2. Stratum Granulosum

3. Stratum Basale

4. Stratum Corneum

The correct answer is: Stratum Basale

The deepest layer of the epidermis is known as the Stratum Basale. This layer is critical for the regeneration of the skin because it is where new skin cells are generated through cell division. The cells created in the Stratum Basale eventually move up through the other layers of the epidermis as they mature and die, contributing to the skin's barrier function. Additionally, the Stratum Basale contains melanocytes, which are cells responsible for producing melanin, the pigment that gives skin its color and protects against UV radiation. This active layer is essential not only for the formation of new cells but also for skin coloration and protection, highlighting its importance in the overall function of the skin. As new cells are formed, they push older cells upward, leading them to eventually reach the uppermost layers, where they become flattened and keratinized.