What does the "horny layer" of the skin refer to?

The "horny layer" of the skin refers to the outermost layer of the epidermis, known as the stratum corneum. This layer is primarily composed of dead skin cells that have undergone a process called keratinization. These dead cells serve a crucial function by forming a protective barrier that seals the skin from various environmental factors, such as bacteria, chemicals, and water loss.

The stratum corneum plays a vital role in maintaining skin hydration by preventing transepidermal water loss, which is essential for overall skin health. While the living skin cells beneath this layer contribute to the hydration and overall function of the skin, it is the dead cells in the horny layer that physically protect the underlying structures, providing a robust defense against external aggressors. This characteristic is what makes the correct answer relevant and significant in the context of skin anatomy and function.