Skin

The image illustrates the structure of the epidermis, the outermost layer of the skin, in a detailed cross-section. The epidermis is depicted as a stratified squamous epithelium, composed of several distinct layers, each with a specific role in skin health and function.

From bottom to top, the labeled layers are:

  1. Stratum Basale (Basal Layer): This is the deepest layer, resting on the dermis. It contains columnar to cuboidal basal cells, which are mitotically active, meaning they divide to form new cells. These new cells then move up through the layers of the epidermis as they differentiate.

  2. Stratum Spinosum (Spiny Layer): Above the basal layer, this layer is named for the spiny appearance of the cells due to desmosomal connections when viewed under a microscope. It provides strength and flexibility to the skin.

  3. Stratum Granulosum (Granular Layer): This layer consists of keratinocytes that have moved from the lower layers. These cells contain granules of keratohyalin, which play a role in water retention and give the cells a grainy appearance.

  4. Stratum Lucidum (Clear Layer): This thin, transparent layer is found only in thick skin, like the skin of the palms and soles. It consists of dead and flattened keratinocytes that provide an additional barrier to injury and infection.

  5. Stratum Corneum (Horny Layer): The outermost layer is made up of dead keratinocytes that have lost their nucleus and cytoplasm and are filled with keratin protein. This layer is highly durable and creates a waterproof barrier.

The progression from young cells at the bottom to old, dead cells at the top is indicated by an arrow labeled “YOUNG” at the basal layer ascending to “OLD” at the stratum corneum. Below the stratum basale is the dermis, which is not part of the epidermis but provides support and nutrition to the epidermal layers.

This cross-sectional view is essential for understanding how the skin renews itself and protects the body, with each layer playing a specialized role in skin physiology.

This image provides a detailed cross-sectional view of human skin, highlighting its various layers and components. The image is structured with labels pointing to specific layers and elements within those layers.

At the topmost layer, we have the Epidermis, which is divided into four distinct strata (from outermost to innermost): the Stratum corneum, Stratum lucidum, Stratum granulosum, and Stratum spinosum, ending with the Stratum basale. These layers collectively serve as the barrier of the skin, with the Stratum corneum being the outermost layer of dead cells that are continuously shed and replaced.

Below the epidermis lies the Dermis, which is further subdivided into two regions: the superficial Papillary region characterized by finger-like projections that interlock with the epidermis, increasing the surface area of contact, and the deeper Reticular region, which provides structural strength and elasticity to the skin due to its dense connective tissue.

The bottom-most layer shown is the Subcutaneous fatty tissue, which insulates the body and acts as an energy reserve, as well as providing cushioning for the skin.

Within these layers, the image also depicts various skin components and receptors:

  • Pain receptors (free nerve endings) that detect painful stimuli.
  • Sweat glands which are involved in thermoregulation and excretion.
  • Sweat ducts leading from the sweat glands to the surface of the skin.
  • Touch receptors that allow the sensation of touch.
  • Nerves that transport signals to and from the brain.
  • Capillaries, small blood vessels that supply the dermis with nutrients and oxygen.
  • Veins which carry deoxygenated blood back to the heart.
  • Pressure receptors that sense mechanical changes in the environment.
  • Arteries that deliver oxygenated blood from the heart to the tissues.

The illustration clearly shows the complexity and functionality of skin, demonstrating its role as a protective barrier, a sensory interface with the environment, and an active player in the body’s thermoregulation and circulatory systems. The interplay of these elements allows the skin to perform its vital functions, including protection against pathogens, synthesis of vitamin D, sensation, and temperature regulation.

This image is a simplified representation of the anatomy of a human fingernail and its surrounding structures.

At the base of the nail, we see the Nail matrix or the Root of the nail, which is the part of the nail bed that extends beneath the skin and is responsible for producing cells that become the nail plate.

The Proximal nail fold is the skin that overlaps the nail matrix, and just below this fold is the Eponychium, commonly known as the cuticle. The cuticle is a layer of clear skin located along the bottom edge of your finger or toe. This area is particularly important for nail health and growth, as it protects the new nail from bacterial infections as it grows out from the nail root.

The Body of the nail is the hard, translucent part of the nail, composed mostly of keratin, which is the visible nail area.

The Nail bed is the skin beneath the body of the nail. The nail bed is rich in blood vessels, giving the nail its characteristic pink color, except at the base where it may look whiter.

On the tip, we have the Free edge of the nail, which is the part of the nail that has grown beyond the end of the finger or toe and is often trimmed during nail care.

Below the nail bed is the Phalanx (bone of fingertip), which is the distal portion of the fingers or toes.

Beneath the proximal nail fold and not visible from the top is the Stratum germinativum, which is the deepest layer of the epidermis and plays a key role in the generation of new skin cells, including those that form the nail plate.

Overall, the image captures the complex structure of the nail, showing how it is more than just a protective keratin plate but is a system integrated with the skin and bone of the fingertip, with specific parts like the nail matrix and eponychium playing crucial roles in nail growth and health. The nail structure supports the delicate tips of the fingers and toes, enhances tactile sensation, and aids in the manipulation of small objects.

This image illustrates the factors that determine hair color and texture in humans. It’s divided into six panels, each showing a hair follicle and a cross-section of the hair shaft corresponding to different hair colors and textures.

The top row of panels depicts the hair follicles and the emerging hair shaft. The leftmost panels show a straight and curly blonde hair, followed by a straight and curly black or brown hair, and ending with straight and curly grey hair on the right. The curly hair follicles have a distinctive hook-like shape, which contributes to the hair’s curliness as it grows.

The bottom row shows cross-sections of the hair shafts corresponding to each type of hair above them. These cross-sections highlight the distribution of two types of melanin pigment: pheomelanin (which is responsible for blonde and red hair colors) and eumelanin (which determines brown and black hair colors). The presence of these pigments within the cortex of the hair shaft gives the hair its color.

In the blonde hair, we see a larger concentration of pheomelanin, which is lighter in color. In the black/brown hair, there is a higher concentration of eumelanin, giving the hair a darker appearance.

The grey hair panels show a reduction in pigment, with more air spaces within the medulla, which is the central core of the hair shaft. This lack of pigment results in the grey or white appearance of the hair.

Each hair shaft is composed of three layers:

  • The Cuticle: the outer layer which is made up of overlapping scales that protect the inner layers of the hair.
  • The Cortex: which contains the melanin and is responsible for the strength and color of the hair.
  • The Medulla: the innermost layer which can be hollow or filled with air or keratin and is not always present in all hair types.

The structure of the hair follicle and the composition of the hair shaft play a significant role in determining the appearance of hair. For example, the shape of the follicle affects the shape of the hair shaft and thus its texture—straight or curly. The presence and proportion of different melanin types within the cortex define the hair color, and the changes in melanin production over time lead to the greying of hair.

This image depicts the process of hair loss in three stages, along with a cross-sectional view of the skin and hair follicles at each stage.

In the first stage on the left, the skin section shows hair follicles with hair shafts protruding from the epidermal layer of the skin. The follicles are embedded in the dermis, and there is a rich network of blood vessels below them. The corresponding circular icon below shows a person with a full head of hair.

Moving to the middle stage, the hair follicles appear to be in a reduced state with shorter hairs not reaching the previous length, indicating that the hair growth has weakened. This is commonly associated with the miniaturization of hair follicles due to various factors such as hormonal changes, nutritional deficiencies, or genetics. The image below this stage shows a person with a noticeably receding hairline and thinner hair on top.

In the final stage on the right, the hair follicles are shown further miniaturized and the hairs have receded below the skin surface, which is now smooth, reflecting significant hair loss. This could be representative of the condition known as baldness or alopecia, where hair fails to grow back due to the follicles losing their ability to regenerate hair. The icon below shows a person with only a fringe of hair remaining around the sides and back of the head, which is a common pattern of hair loss in male-pattern baldness.

Overall, this illustration summarizes the progression of hair loss, showing how it can lead from a full head of hair to a state where the hair follicles no longer produce visible hairs above the skin. The health and function of the hair follicles are crucial for hair retention, and their gradual diminishment can lead to the common condition of baldness.

This image is a detailed representation of skin pigmentation and the layers of the skin involved in this process.

Starting from the top layer:

  • The Stratum corneum is the outermost layer, consisting of dead keratinized cells that form a protective barrier.
  • The Stratum lucidum is a thin, clear layer found only in certain parts of the body like the palms of the hands and the soles of the feet.
  • The Stratum granulosum beneath has granules that contribute to waterproofing the skin.

In the middle section, we see the Stratum spinosum, where cells appear spiny as they begin to dry out and flatten.

The deepest epidermal layer is the Stratum basale, which is a single row of cells primarily made up of keratinocytes. This layer is significant for pigmentation because it contains melanocytes, the cells that produce melanin—the pigment responsible for the color of the skin. Melanin is visible in the image as darker spots within the cells. These melanin granules are transferred from the melanocytes to the keratinocytes and move upward through the epidermal layers, giving the skin its color.

The bottommost layer shown is the Dermis, which is not directly involved in pigmentation but provides support and nutrition to the epidermis.

This visual representation underscores the role of the Stratum basale in the pigmentation process, with melanocytes producing melanin and passing it to the surrounding keratinocytes. Skin color variation among individuals is largely due to differences in the type and amount of melanin produced by the melanocytes, which is genetically determined and can also be influenced by exposure to sunlight.

The image depicts the skin condition known as Varicella Zoster, which is the virus responsible for chickenpox in the initial infection and shingles upon reactivation.

At the skin surface, we see blisters that develop, resembling chickenpox and filling with pus, which is typical of a shingles outbreak. These blisters are a response to the viral infection in the skin cells.

Below the surface, the image illustrates the initial stage of the infection, marked by red spots representing areas of burning pain and sensitive skin. This corresponds to the prodromal symptoms of shingles, where pain often precedes the rash.

The deeper layers show the relationship between the virus and the nervous system. We see the Varicella Zoster virus reactivating within a nerve fiber. The virus, which had been dormant in the nerve ganglia after an initial chickenpox infection, can become active again, typically during periods of weakened immune system, which is also noted in the image.

The virus’s presence in the nerve fibers leads to nerve damage, which can cause postherpetic neuralgia—a condition of persistent pain in the area of the shingles rash even after the rash has cleared.

Finally, the image indicates that eventually, the blisters burst, and they form a scab as they heal. This is the body’s natural process of recovering from the blistering rash associated with shingles.

The image summarizes the progression of a shingles infection from the reactivation of the dormant virus to the development of painful skin lesions and potential nerve damage, emphasizing the connection between the virus, skin symptoms, and the nervous system.

This image illustrates a wart and its underlying cause on human skin. A wart is an overgrowth of skin cells on the epidermis caused by the human papillomavirus (HPV).

The main part of the image shows a cross-section of the skin with a wart protruding from the surface. The wart is depicted as an irregular, rough growth on the skin, comprising clumps of epithelial cells that have proliferated excessively due to the viral infection.

Below the wart, we see the virus (HPV) within the deeper layer of the skin, indicating that it infects the cells in the basal layers of the epidermis. The virus causes these cells to grow rapidly, leading to the formation of the wart on the skin surface.

In the detailed inset, we can see the HPV particles, marked by red spots, infecting an epithelial cell. This close-up view is meant to emphasize the viral cause of the wart.

The image also shows the underlying dermis with a network of capillaries (small blood vessels), highlighted in blue and red, which supply nutrients and oxygen to the skin layers. While warts are generally considered benign, they are fed by these blood vessels, which sustain the infected and overgrown tissue.

Overall, this visualization demonstrates how a common virus can alter the behavior of skin cells, leading to a visible manifestation on the skin’s surface. Warts are typically harmless and can resolve on their own, but they are contagious and can be spread through direct contact.

This image depicts the progression of a Herpes zoster infection, commonly known as shingles, which is a reactivation of the Varicella Zoster Virus (VZV) -- the same virus that causes chickenpox.

The first panel on the top left illustrates early symptoms, where ‘The Bumps turn blisters with fluid’. Here, we see the skin’s surface with several raised, fluid-filled blisters.

The second panel on the top middle is labeled ‘Dormant virus’. It shows a cross-section of skin with the virus lying inactive near the nerve fibers, beneath the skin. This is the stage where the virus is not causing any symptoms.

Moving to the top right panel, it says ‘The blisters break open’, depicting the stage where the blisters have ruptured, creating open sores on the skin surface.

The bottom left panel shows ‘Reactivation of the Virus’, where the VZV, which has been dormant within the nerve fibers, reactivates and travels along the nerve to the skin, causing the characteristic painful rash.

The center bottom panel is labeled ‘Awakened virus Herpes zoster’, highlighting the active phase of the virus as it causes the rash and blisters associated with shingles.

Finally, the bottom right panel indicates ‘The sores crust disappear in two four weeks’, where the blisters have dried out and formed crusts that eventually fall off, and the skin heals over a period of two to four weeks.

To summarize, this illustration captures the lifecycle of a shingles outbreak, from the initial skin bumps turning into fluid-filled blisters, to the opening and crusting of these blisters, and the eventual healing of the sores. It also shows the underlying cause, which is the reactivation of the VZV from its dormant state in the nerve fibers, leading to the painful and characteristic skin manifestations.

This image is a detailed cross-section of human skin, showcasing the various components and their relationship to one another.

At the very top, we have the surface layer called ‘keratin (stratum corneum)’ which is the tough, protective outer layer of the skin made of keratinized cells. Just beneath it, we see ‘Hair’ protruding through the ‘Pore’, which is the opening on the skin surface.

The ‘Epidermis’ is the outermost layer of skin depicted just below the keratin layer, followed by the ‘Dermis’, which is a thicker layer containing the structural elements of the skin. Within the dermis, you can see ‘The capillaries’, which are tiny blood vessels that supply the skin with nutrients and oxygen.

Below the dermis is the ‘Subcutaneous fat cell’ layer, often referred to as the hypodermis or subcutis, which provides insulation and cushioning for the skin.

In terms of structures, the image shows a ‘Hair follicle’, which is the sheath surrounding the hair root, and associated with it is the ‘Muscle, levator hair’ also known as the arrector pili muscle, which can cause hair to stand up when it contracts.

There are also ‘Sweat gland’ and ‘Sebaceous gland’ (labeled as ‘Solo gland’), which are part of the skin’s thermoregulation and lubrication systems, respectively. Sweat glands produce sweat to help cool the body, while sebaceous glands secrete sebum to keep the skin and hair moisturized.

‘Fat slices’ are shown as yellow clusters at the bottom, depicting the fatty tissue layer.

‘Nerve end’ fibers are illustrated as blue thread-like structures intertwined with the dermis, highlighting the sensory component of the skin that allows us to feel touch, pain, and temperature.

Lastly, ‘Blood vessels’ are depicted in red and blue, illustrating the flow of blood to and from the heart, which is crucial for delivering nutrients and removing waste from the skin.

In summary, the image captures the complexity of the skin, emphasizing its role as a protective barrier, a sensory interface, and a complex organ involved in various physiological processes like temperature regulation and secretion. It highlights the skin’s multi-layered structure, vascular supply, innervation, and its various appendages like hair and glands.

This diagram provides a comprehensive look at the skin and its components, both as an overview and in detailed insets showing specific structures.

Central to the image is a cross-section of the skin, illustrating its various layers and embedded structures. From the bottom up, we see the fatty ‘Adipose tissue’, which acts as insulation and energy storage. Above this layer are networks of ‘Nerves’ and ‘Blood vessels’, including ‘Arteries’ that carry oxygenated blood to the skin and ‘Veins’ that carry deoxygenated blood away.

The skin itself is represented in three main layers. The deepest layer shown is where the ‘Hair papilla and capillaries’ reside, supplying nutrients to the hair root. The ‘Hair root plexus’ is a network of nerve fibers surrounding the hair follicle that detects hair movement. ‘Pacinian corpuscles’ are also depicted, responsible for sensing deep pressure and vibration.

In the middle layer, ‘Sebaceous glands’ connected to the hair follicle produce oil to lubricate the skin and hair. ‘Sweat glands’ are shown as coiled tubular structures that secrete sweat to the skin’s surface, aiding in temperature regulation. The ‘Hair root’ anchors the hair into the skin, and the ‘Arrector pili muscle’ can contract to cause the hair to stand erect, which is part of the body’s response to cold or fear.

The top layer, the epidermis, includes ‘Free nerve endings’ which sense pain and temperature, and ‘Meissner corpuscle’ which are sensitive to light touch. Also shown are ‘Merkel cells’, which function as mechanoreceptors responsible for the sense of touch.

Insets around the main image provide a closer look at individual elements, such as the ‘Sebaceous gland’, ‘Sweat gland’, ‘Artery’, ‘Vein’, ‘Adipose tissue’, ‘Nerve’, ‘Hair root’, ‘Pacinian corpuscle’, and ‘Merkel cells’. Each inset is labeled and shows the structure in greater detail.

Overall, this image conveys the skin’s complexity as an organ system, highlighting its role in protection, sensation, thermoregulation, and interaction with the environment. It provides a snapshot of the many different cell types and structures that work together to perform these vital functions.

This image is a detailed cross-sectional illustration of human skin, highlighting several distinct layers and cellular components.

At the top layer, we see the ‘Stratum corneum,’ which is the outermost part of the ‘Epidermis.’ This layer is composed of dead, flattened skin cells that serve as a barrier to protect underlying tissues.

Just beneath the stratum corneum, within the epidermis, we see cells labeled as ‘Melanocyte’ and ‘Basal cell.’ Melanocytes are responsible for producing melanin, the pigment that gives skin its color and protects it from UV radiation. Basal cells represent the bottom layer of the epidermis and are involved in producing new skin cells.

The ‘Sebaceous gland’ is shown associated with a hair follicle, secreting an oily substance known as sebum that helps to keep the skin moisturized and protected.

Below the epidermis is the ‘Dermis’ layer, which houses ‘Blood vessels’ that supply the skin with nutrients and oxygen. Also depicted are ‘Free nerve endings’ that are involved in the sensation of pain, heat, and cold.

Further down is the ‘Hypodermis,’ which is primarily composed of ‘Adipocytes,’ or fat cells, providing insulation and cushioning for the body.

Lastly, at the bottom of the image, there’s the ‘Muscle layer.’ While not typically part of the skin, the muscle layer is crucial for movement and support, and it lies beneath the hypodermis.

This diagram effectively demonstrates the skin’s structure and function as a protective barrier, a sensory organ, and an interface with the body’s internal structures. It emphasizes the skin’s role in protecting from external damage, regulating temperature, and providing sensory information.

This colorful and detailed image is a comprehensive skin anatomy diagram. It combines an overview of the skin’s structure with detailed insets of various sensory receptors and skin components.

The central part of the image shows a cross-section of the skin, with the various layers labeled. The ‘Epidermis’ is the outermost layer, subdivided into the ‘Stratum basale,’ ‘Stratum spinosum,’ ‘Stratum granulosum,’ ‘Stratum lucidum’ (only present in certain parts of the body like the palms and soles), and the ‘Stratum corneum’ at the very top. The ‘Dermis’ sits below the epidermis, followed by the ‘Subcutaneous tissue’ which consists mainly of adipose tissue.

Embedded within these layers are structures such as the ‘Hair root’ and ‘Sweat gland,’ each playing vital roles in the skin’s function. The ‘Sebaceous (solo) gland’ is shown connected to the hair follicle, secreting sebum that conditions the hair and skin.

Insets around the main diagram focus on the sensory receptors and appendages. The ‘Pacinian corpuscle’ is a large, onion-like structure responsible for sensing deep pressure and vibration. Its detailed structure is shown with its many concentric layers of connective tissue that encase a nerve ending.

The ‘Meissner corpuscle,’ responsible for light touch sensitivity, is depicted as a more elongated structure within the dermal papillae. The ‘Merkel disc,’ a touch receptor, is shown with its associated nerve ending. ‘Krause end bulbs,’ thought to be involved in the sensation of cold, appear as bulbous structures. ‘Ruffini endings,’ which detect stretch and warmth, are also illustrated.

We can also see ‘Free nerve endings’ that permeate the skin layers and are involved in pain, temperature, and mechanical stress detection. ‘Arteries’ and ‘veins’ are represented, indicating the vascular supply of the skin.

The large inset on the left side is a detailed illustration of a ‘Pacinian corpuscle,’ showing its layered capsule and the nerve ending within.

In the top right corner, the diagram also depicts the ‘Layers of connective tissue with blood vessels’ and ‘Capillaries’ within the nervous structure, emphasizing the skin’s complex vascularization.

At the bottom, the labels ‘Nerve,’ ‘Artery,’ ‘Ruffini endings,’ ‘Vein,’ and ‘Adipose tissue’ are color-coded to match the structures within the main diagram.

Overall, this image illustrates the skin’s complexity as an organ, highlighting its role in protection, sensation, thermoregulation, and interaction with the environment. It underscores the diversity of specialized cells and structures that allow the skin to perform its various functions.

This image provides a visual explanation of the four degrees of burns that can affect the skin and underlying tissues. Each panel shows a different degree of burn severity, progressing from first to fourth degree.

The top left panel illustrates a ‘First-degree burn’, which is characterized by redness without blisters. It affects only the ‘Epidermis’, the outermost layer of the skin. First-degree burns are usually painful and may cause minor inflammation.

The top right panel depicts a ‘Second-degree burn’, identifiable by blisters and very painful. This type of burn extends through the epidermis and into the ‘Dermis’, causing more severe damage which includes swelling and the risk of infection.

The bottom left panel shows a ‘Third-degree burn’. It is described as an area that is stiff and the injury extends through all layers of the skin. In this type of burn, both the epidermis and dermis are destroyed, and there can be damage to the ‘Fat’ layer beneath. The nerve damage in third-degree burns may cause numbness.

Finally, the bottom right panel represents a ‘Fourth-degree burn’, which is the most severe. It describes an injury to deeper tissues (muscle, tendons, bones). Here, the burn extends beyond all layers of the skin and into the underlying ‘Muscle’, and potentially even deeper into tendons and bones. These burns are often life-threatening and can lead to significant scarring and loss of function.

The image effectively categorizes the burn degrees by depth of skin and tissue damage, providing a clear visual for understanding the severity and potential complications of each type.

This image depicts an illustration of a woman with annotations pointing to examples of different types of scars that can form on the skin.

The ‘Atrophic’ scar is typically characterized by a sunken appearance, because the skin underlying the scar has been lost; these scars are common with conditions like acne.

A ‘Keloid’ scar is illustrated as a raised, reddish nodular scar that goes beyond the boundary of the original wound. Keloid scars are the result of an overly aggressive healing process and continue to grow, even after the wound has healed.

‘Contracture’ scars are shown as tightened skin that can limit movement. This type of scar usually forms after the skin has been burned. It may involve not just the skin but the underlying muscles and tendons, causing a contracture.

‘Stretch Marks’ are a form of scarring on the skin with an off-color hue. They are caused by tearing of the dermis, which over time may diminish but will not disappear completely.

Finally, ‘Hypertrophic’ scars are thick, raised scars that are similar to keloids but do not go beyond the boundary of the injury. They may reduce in size over time.

The image serves as an educational tool to distinguish between various scar types, showing where they might typically appear on the body and what their general characteristics are.

This image provides a visual overview of common skin problems, each represented by a stylized icon.

The first row shows ‘Acne’, depicted by two icons: one showing red pimples with white pus-filled tips on the skin, and the other showing a close-up cross-section of a hair follicle clogged with sebum and dead skin cells, which is typical in acne.

‘Dark eye circles’ are illustrated with an eye icon showing dark shading underneath, which can be due to various factors, including fatigue or genetics.

‘Vitiligo’ is represented by a patch of skin with a significant loss of pigmentation, which is characteristic of this condition where melanocytes (the cells that produce pigment) are destroyed.

The second row displays ‘Pimples’, similar to the acne icons, but focused on the swollen red bumps on the skin’s surface.

‘Whiteheads’ are depicted as white, raised spots on the skin, indicating a type of acne lesion that occurs when dead skin cells, oil, and bacteria become trapped within one of your pores.

‘Wrinkles’ are shown as lines and creases in the skin, commonly associated with aging.

In the third row, ‘Blackheads’ are presented as darkened pores on the skin, another type of acne that occurs when pores are clogged with oil and dead skin cells, the dark surface is due to the oxidation of the debris inside the pore.

‘Dry skin’ is depicted with a cracked texture, indicating the lack of moisture that can lead to a rough and flaky appearance.

Another ‘Wrinkles’ icon closes the visual list, this time focusing on the eye area, showing crow’s feet which are the lines that radiate from the corners of the eyes.

This image serves as an easy-to-understand guide to identifying common skin issues, each with its unique features and visual markers.

This image displays a detailed diagram of the anatomy of the fingernail, featuring both a dorsal view of the finger and cross-sectional views to illustrate the various components.

In the dorsal view on the left, we can see:

  1. ‘Free edge’ -- the portion of the nail that extends beyond the finger, which has no underlying skin.
  2. ‘Nail plate’ -- the hard, translucent part of the nail, made of keratin.
  3. ‘Lateral nail fold’ -- the fold of skin at the side of the nail.
  4. ‘Lunula’ -- the whitish half-moon shape at the base of the nail, which is part of the nail matrix.
  5. ‘Cuticle’ -- the thin tissue that overlaps the nail plate at the base of the nail.
  6. ‘Proximal nail fold’ -- the fold of skin that covers the nail matrix.
  7. ‘Hyponychium’ -- the area of epithelium, particularly sensitive skin, under the free edge of the nail plate.
  8. ‘Nail bed’ -- the skin beneath the nail plate.

In the cross-sectional view on the right, the following structures are indicated:

  1. ‘Nail plate’ -- as seen in cross-section.
  2. ‘Nail root’ -- the proximal part of the nail under the skin, where nail growth begins.
  3. ‘Nail matrix’ -- the tissue (often under the skin) that the nail protects, which generates the cells that become the nail plate.
  4. ‘Hyponychium’ -- under the free edge, as described above.
  5. ‘Eponychium’ -- the living tissue that emerges from the proximal nail fold and attaches to the nail plate. It is often mistaken for the cuticle.
  6. ‘Dermis’ -- the dense inner layer of skin beneath the epidermis, which contains nerve endings and blood vessels.
  7. ‘Capillaries and veins’ -- the blood vessels providing circulation to the nail bed and matrix.
  8. ‘Distal phalanx’ -- the bone beneath the nail bed.

The additional, smaller cross-sectional view at the bottom highlights the nail plate’s structure over the nail bed and the surrounding tissue.

Overall, the image serves as an informative tool, offering a clear visual representation of the fingernail’s structure and its different components, which are crucial for its growth and health.

TermDefinition
Stratum Basale (Basal Layer)The deepest layer of the epidermis, containing basal cells that are mitotically active, producing new skin cells.
Stratum Spinosum (Spiny Layer)The layer above the basal layer, named for the spiny appearance of cells due to desmosomal connections, providing strength and flexibility.
Stratum Granulosum (Granular Layer)The layer where keratinocytes accumulate granules of keratohyalin, contributing to water retention and barrier function.
Stratum Lucidum (Clear Layer)A thin, transparent layer found only in thick skin, consisting of dead and flattened keratinocytes.
Stratum Corneum (Horny Layer)The outermost layer made of dead keratinocytes that forms a durable, waterproof barrier.
DermisThe supportive layer below the stratum basale, providing nutrition to the epidermis, not an epidermal layer but included for context.
Papillary RegionThe superficial area of the dermis with projections that increase the surface area of contact with the epidermis.
Reticular RegionThe deeper part of the dermis providing structural strength and elasticity due to dense connective tissue.
Subcutaneous Fatty TissueThe bottom-most layer acting as insulation, an energy reserve, and cushioning for the skin.
Pain ReceptorsFree nerve endings that detect painful stimuli.
Sweat GlandsInvolved in thermoregulation and excretion.
Touch ReceptorsAllow the sensation of touch.
CapillariesSmall blood vessels that supply the dermis with nutrients and oxygen.
Pressure ReceptorsSense mechanical changes in the environment.
Nail MatrixThe tissue at the base of the nail bed responsible for producing cells that become the nail plate.
Proximal Nail FoldThe skin overlapping the nail matrix.
Eponychium (Cuticle)A layer of clear skin along the bottom edge of the finger or toe, protecting new nail from bacterial infections.
Nail BedThe skin beneath the body of the nail, which is rich in blood vessels.
Free EdgeThe part of the nail that extends beyond the finger or toe.
Phalanx (bone of fingertip)The distal portion of the fingers or toes.
Stratum GerminativumThe deepest layer of the epidermis involved in generating new skin cells.
MelanocyteA cell in the stratum basale that produces the pigment melanin, giving skin its color and protecting against UV radiation.
Dendritic CellsImmune cells within the stratum spinosum that respond to pathogens.
Basement MembraneA thin layer that anchors the epidermis to the dermis.
LunulaThe whitish half-moon shape at the base of the nail, visible part of the nail matrix.
Lateral Nail FoldThe fold of skin at the side of the nail.
HyponychiumThe area of sensitive skin under the free edge of the nail plate.
Nail RootThe part of the nail under the skin where nail growth begins.
Distal PhalanxThe bone beneath the nail bed.

Practice Quiz