Skin Layers and Their Functions

The skin has three basic layers, each with a different role

Moisturiser isn't just for the face
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Skin is the largest organ in the body and is quite complex. You have three main skin layers that are made up of many specialized cells and structures.

The skin's primary function is to act as a barrier against disease-causing pathogens (germs) and hostile environments. It also helps regulate body temperature and gathers sensory information from your environment.

The article looks at the skin layers—the epidermis, dermis, and subcutaneous tissue, what they're made of, and why they're important to your health.

layers of the skin
 Verywell / Alexandra Gordon

The Epidermis

The epidermis is the outermost skin layer. Its thickness depends on where it is on the body. It's thinnest on the eyelids (roughly half a millimeter) and thickest on your palms and soles (1.5 millimeters).

The epidermis is made up of five layers.

Stratum Corneum

The stratum corneum is the top layer of the epidermis. Its jobs are to:

  • Helps your skin retain moisture
  • Keep unwanted substances out of your body

It is made of dead, flattened cells called keratinocytes that are shed approximately every two weeks. Keratinocytes produce keratin, a fibrous protein that helps provide structure to your skin, hair, and nails.

Stratum Lucidum

The stratum lucidum is a separate layer only in the thicker epidermis on the palms of the hands and soles of the feet. In thinner areas, its cells and functions are incorporated into other layers.

The stratum lucidum:

  • Allows the skin to stretch 
  • Contains a protein that helps skin cells degenerate
  • Protects your palms and soles from the effects of friction
  • Makes your skin waterproof

This layer is also made of dead, flattened keratinocytes.

Stratum Granulosum 

The stratum granulosum layer contains keratinocytes that are gradually being pushed toward the surface of the skin. While moving through this layer, cells start to lose their structure and characteristic and become more like the dead, flattened kerotinocytes of the outermost layers.

This skin layer also contains lipids (a type of fatty acid) that help form a waterproof barrier that prevents your body from losing fluid through the skin.

Stratum Spinosum

The stratum spinosum, or squamous cell layer, is the thickest part of the epidermis. It contains:

This is the main barrier that keeps foreign substances in the environment from getting into your body.

Stratum Basale

Also called the basal cell layer, the stratum basale is the bottom layer of the epidermis. It contains several important types of cells:

  • Column-shaped stem cells that push older kerotinocytes toward the surface, where they flatten and die
  • Melanocytes, which produce pigment that gives your skin its color
  • Merkel cells, which sense touch

The Dermis

The dermis is the middle layer of the skin. It contains connective tissue, capillaries, nerve endings, and hair follicles. It also contains different glands, including sebaceous glands that produce sebum (a body oil) and apocrine glands that produce sweat.

The dermis is split into two parts.

Papillary Dermis

The papillary dermis is the thin, upper layer that contains capillaries (tiny blood vessels) that help regulate skin temperature and provide nutrients to the epidermis.

This skin layer also contains:

  • Meissner corpuscles, which are receptors that transmit sensations of delicate touch
  • Lamellar corpuscles, which are receptors that transmit sensations of vibration and pressure

Reticular Dermis

The reticular dermis is the thick, lower layer that contains connective tissues and dense collagen bundles.

Collagen is the main protein that provides structure to skin and connective tissues. It gives skin its elasticity and strength.

The thickness of the dermis varies by its location on the body. On the eyelids, it is roughly 0.6 millimeters thick. On the back, palms of hands, and soles of the feet, it's 3 millimeters thick.

Subcutaneous Tissue

Subcutaneous tissue is the innermost layer of the skin. It's mostly made up of:

  • Fat
  • Connective tissues
  • Larger blood vessels
  • Nerves

The majority of your body fat is stored in the subcutaneous layer. It insulates you against changing temperatures and protects your muscles and internal organs from impacts and falls.

The subcutaneous layer also:

  • Stores fat cells for energy reserves
  • Gives the body its smooth, contoured appearance
  • Regulates temperature through the contraction and dilation of blood vessels
  • Serves as the attachment point for bones, muscles, and other organs to the skin
  • Contains deep pressure sensors
  • Produces a hormone called leptin that helps keep the body's metabolism in homeostasis (balance among all of your body's systems so they can function well)

Summary

The skin is the body's largest organ. It is made of three layers, each of which has specific functions.

The outermost epidermis is responsible for producing new skin cells, protecting the body from unwanted substances, and retaining moisture to keep the skin well hydrated.

The middle dermis is responsible for supporting and strengthening the skin. It helps keep the skin moisturized and nourishes the epidermis. It also aids with fine sensations and helps regulate the skin temperature.

The innermost subcutaneous tissue insulates the body against changes in temperature and physical impacts. It gives the body its contoured shape and connects the skin to the internal organs. It also stores fat cells for energy and helps regulates the body temperature,

Frequently Asked Questions

  • How many layers of skin are there?

    There are three main layers of skin:

    • Epidermis: The outermost layer, which contains five sub-layers
    • Dermis: The middle layer, which consists of two parts known as the papillary dermis (thin, upper layer) and the reticular dermis (thick, lower layer)
    • Subcutaneous tissue: The deepest layer of skin
  • What is the integumentary system?

    The integumentary system is a collection of organs that includes the skin, hair, nails, endocrine glands, and sensory nerves. The primary function of this system is to protect the body from external elements, such as bacteria or pollution.

  • Which layers of the skin are affected by third-degree burns?

    Third-degree burns affect all layers of skin: the epidermis, dermis, and subcutaneous tissue. These burns may require skin grafting treatments since the damage is so severe that the skin might be unable to repair itself.

  • When getting tattooed, which layer of the skin is the ink injected into?

    Tattoo needles penetrate the epidermis and place ink into the dermis, about 2 millimeters below the skin’s topmost layer. Injecting the pigment this deeply prevents the ink from wearing away so it can remain permanently visible.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Abdo J, Sopko N, Milner S. The applied anatomy of human skin: A model for regeneration. Wound Medicine. 2020;28:100179. doi:10.1016/j.wndm.2020.100179

  2. Ono S, Kabashima K. Novel insights into the role of immune cells in skin and inducible skin-associated lymphoid tissue (iSALT). Allergo J Int. 2015;24:170-179. doi:10.1007/s40629-015-0065-1

  3. National Institutes of Health, U.S. National Center For Biotechnology Information: StatPearls [Internet]. Histology, dermis.

  4. Shpichka A, Butnaru D, Bezrukov E, et al. Skin tissue regeneration for burn injury. Stem Cell Res Ther. 2019;10(1):94. doi:10.1186/s13287-019-1203-3

  5. Tolles J. Emergency department management of patients with thermal burns. Emerg Med Pract. 2018;20(2):1-24.

  6. Islam PS, Chang C, Selmi C, et al. Medical complications of tattoos: a comprehensive review. Clinic Rev Allerg Immunol. 2016;50(2):273-286. doi:10.1007/s12016-016-8532-0

Additional Reading
  • Kumar V, Abbas AK, Aster JC. Robbins and Cotran Pathologic Basis of Disease. Philadelphia: Elsevier Saunders.

  • National Institutes of Health, U.S. National Center For Biotechnology Information: StatPearls [Internet]. Anatomy, skin (integument),epidermis.

By Heather L. Brannon, MD
Heather L. Brannon, MD, is a family practice physician in Mauldin, South Carolina. She has been in practice for over 20 years.