Which layer of the epidermis is also known as the "horny layer"?

The layer of the epidermis referred to as the "horny layer" is the stratum corneum. This outermost layer serves as the skin's primary barrier to the environment. The stratum corneum is composed of dead skin cells that have been keratinized, which means they have been filled with keratin, a tough and protective protein. This layer plays a crucial role in protecting underlying tissues from pathogens, chemicals, and physical abrasions while also helping to prevent moisture loss from the body. The term "horny" relates to the tough nature of the cells, reminiscent of horns found in animals.

In this context, the other layers have different characteristics and functions. For example, the stratum lucidum is found only in thick skin areas and provides an additional layer of protection, while the stratum germinativum is where new cells are generated through mitosis. The stratum granulosum acts as a transitional layer between living and dead skin cells, contributing to keratin production but does not serve the same protective role as the stratum corneum.