What is the tough "horny" superficial layer of the epidermis known as?

The tough "horny" superficial layer of the epidermis is indeed referred to as the stratum corneum. This layer consists of dead keratinized skin cells that provide a robust barrier against environmental hazards, such as pathogens, chemicals, and physical trauma. The cells in the stratum corneum are filled with keratin, a tough protein that contributes to the layer's protective qualities.

Additionally, the stratum corneum plays a crucial role in preventing water loss, thereby helping to maintain hydration within the underlying layers of the skin. The continuous shedding and renewal of cells in this layer are essential for maintaining healthy skin.

In contrast, the other layers mentioned serve different functions. The stratum lucidum, for example, is found only in thicker skin (such as the palms and soles) and provides an additional layer of protection. The stratum granulosum contains cells that begin to lose their nuclei and become keratinized, contributing to the forming of the stratum corneum. Lastly, the stratum basale is the deepest layer, responsible for generating new skin cells that migrate upward to replenish the upper layers. Each layer has its distinct role, but the stratum corneum is specifically designed to function as the extreme