anatomy-rossi

Subcutaneous layer (Hypodermis)

Deep tissue layer that anchors skin to underlying structures, stores fat, insulates, and cushions against injury.

Keratinocytes

Epidermal cells that synthesize structural proteins and provide water resistance to the skin.

Melanocytes

Specialized cells in the stratum basale that synthesize protective pigment for the skin and hair.

Langerhans cells

Dendritic immune cells residing in the stratum spinosum that help defend against pathogens.

Merkel cells

Sensory receptor cells located in the stratum basale that detect light touch.

Stratum corneum

Outermost epidermal layer composed of flattened, dead, cornified cells that regularly shed.

Stratum lucidum

Thin, translucent layer of dead cells situated between the granulosum and corneum, present exclusively in thick skin.

Stratum granulosum

Middle epidermal layer containing keratohyalin and lamellar granules where cells begin to die.

Stratum spinosum

Epidermal layer characterized by bundles of pre-keratin filaments that give cells a prickly appearance; contains dendritic immune cells.

Stratum basale

Deepest epidermal layer attached to the dermis where rapid cell division produces new skin cells.

Basal cell carcinoma

Common, slow-growing skin cancer originating in the deepest stratum and typically presenting as a shiny bump.

Squamous cell carcinoma

Malignant skin cancer arising from keratinocytes that has the potential to spread.

Melanoma

Highly aggressive and dangerous skin cancer arising from pigment-producing cells.

Free edge

Distal portion of the nail plate extending beyond the tip of the finger or toe.

Nail plate

Hard, visible, translucent keratinized structure covering the dorsal surface of the digit.

Lunula

Pale, crescent-shaped area located at the proximal base of the nail plate.

Eponychium

Narrow band of epidermis (cuticle) extending onto the proximal border of the nail plate to protect against infection.

Nail matrix

Thickened proximal epithelial area beneath the nail root responsible for ongoing nail growth.

Dermal papillary layer

Superficial zone of the dermis forming ridges that project into the epidermis, housing capillary loops and tactile corpuscles.

Dermal reticular layer

Deeper, thicker dermal layer composed of dense irregular connective tissue, collagen bundles, and deep pressure receptors.

Meissner corpuscles

Encapsulated tactile nerve endings located in dermal papillae that respond to light touch.

Pacinian corpuscles

Lamellated sensory receptors found deep in the dermis that detect vibration and deep pressure.

Functions of hair

Sensory reception, physical protection from sunlight and foreign debris, and thermal insulation.

Thick skin

Hairless skin variety located exclusively on the palms of the hands and soles of the feet.

Arrector pili muscle

Small bundle of smooth muscle fibers attached to hair follicles whose contraction raises the hair shaft and produces goosebumps.

Sebaceous glands

Exocrine structures associated with hair follicles that secrete an oily lipid mixture to lubricate and waterproof the skin.

Eccrine sweat glands

Widely distributed tubular glands that open directly onto the skin surface to produce watery fluid for thermoregulation.

Apocrine sweat glands

Coiled tubular glands emptying into hair follicles in axillary and anogenital regions, active after puberty.

Ceruminous glands

Modified exocrine structures situated in the external acoustic meatus that produce earwax.

Keratin

Insoluble, fibrous structural protein that confers strength and water resistance to hair, nails, and the epidermis.

Melanin

Dark pigment produced in granules that determines skin, hair, and eye color while shielding DNA from UV radiation.

Sebum

Oily lipid secretion produced by cutaneous glands to soften skin and inhibit bacterial growth.

Cerumen

Waxy substance secreted into the ear canal that traps foreign particles and repels insects.