Which layer is also known as the horny layer and is the outermost layer of the epidermis?

Which layer is also known as the horny layer and is the outermost layer of the epidermis?

• A. Sebum
• B. Stratum corneum
• C. Hair bulb
• D. Stratum lucidum

Answer: (B)

The outermost protective surface of the skin is the horny layer, known as the stratum corneum. This layer is made up of dead, flattened keratinocytes filled with keratin, which have lost their nuclei and form a tough, water-resistant shield. New cells are produced in the deepest layer and migrate upward, becoming keratinized as they reach the surface and eventually shedding off. This keratinized, “horny” presentation is what gives the layer its name and its protective function against friction, chemicals, and water loss. The other options aren’t layers of the epidermis: sebum is an oily secretion; the hair bulb is part of a hair follicle; and stratum lucidum is a thin layer found only in thick skin, not the outermost surface.

The outermost protective surface of the skin is the horny layer, known as the stratum corneum. This layer is made up of dead, flattened keratinocytes filled with keratin, which have lost their nuclei and form a tough, water-resistant shield. New cells are produced in the deepest layer and migrate upward, becoming keratinized as they reach the surface and eventually shedding off. This keratinized, “horny” presentation is what gives the layer its name and its protective function against friction, chemicals, and water loss. The other options aren’t layers of the epidermis: sebum is an oily secretion; the hair bulb is part of a hair follicle; and stratum lucidum is a thin layer found only in thick skin, not the outermost surface.