Foot Care Nurse Course
Module 2: Anatomy & Physiology of the Foot

Lesson 2: Skin and Nail Structure of the Foot

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Module 2 · Lesson 2 — Skin & Nail Structure of the Foot
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Module 2 · Lesson 2

Skin & Nail Structure of the Foot

Estimated time: 22 min Anatomy
Learning Objectives

By the end of this lesson, the learner will be able to:

  1. Describe the three layers of foot skin and the principal function of each.
  2. Identify common foot skin conditions — calluses, heel fissures, tinea pedis, and diabetic foot ulcers — and recognize their typical presentations.
  3. Identify the components of a healthy toenail and recognize common nail pathologies, including onychomycosis and ingrown toenails.
  4. Apply evidence-based principles for assessment and nursing care of foot skin and nails.

Foot skin is unlike skin anywhere else on the body. It is thicker on the soles, has more sweat glands and fewer oil glands, and serves as the body's first defense against infection — a defense that becomes critical in patients with diabetes, vascular disease, or limited mobility. Combined with the nail unit, the integument is where most foot care problems begin and where nurses have the most direct opportunity to intervene.

The Three Layers of Foot Skin

Each layer plays a different role, and each gives rise to its own set of clinical concerns.

Cross-section of foot skin layers A simplified cross-section showing three layers: epidermis at the top, dermis in the middle with nerve endings, blood vessels, and a sweat gland, and the subcutaneous fatty layer beneath. EPIDERMIS Protection layer DERMIS Sensory & vascular SUBCUTANEOUS Fat / cushion nerve vessel sweat gland
Cross-section of plantar skin showing the three principal layers and key dermal structures
Layer 1 · Top
Epidermis

The outer, waterproof, keratinized layer that protects against friction, infection, and moisture loss. Forms protective calluses where pressure is repeated.

Clinical relevance Thickened calluses on heels or under the metatarsal heads are the epidermis adapting to chronic pressure or friction.
Layer 2 · Middle
Dermis

Contains nerve endings, blood vessels, sweat glands, collagen, and elastin. Responsible for sensation, perfusion, and thermoregulation.

Clinical relevance Damage or dysfunction at this layer — as with diabetic neuropathy — silences pain and pressure signals, allowing wounds to develop unnoticed.
Layer 3 · Deepest
Subcutaneous

A layer of adipose and connective tissue providing shock absorption and insulation, particularly under the heel and ball of the foot.

Clinical relevance Heel pad atrophy in older adults reduces cushioning over the calcaneus, raising the risk of pressure injuries in immobile patients.

Common Skin Conditions

Four conditions account for the majority of skin findings nurses encounter in foot care.

Calluses & Corns
CauseRepeated friction or pressure — ill-fitting footwear, gait abnormalities.
AppearanceThickened, hardened skin, often yellow or grayish; corns are smaller and conical.
CareConservative debridement, moisturization, address underlying mechanical cause.
Suggested Photo
Plantar callus under the first metatarsal head — yellowish, well-demarcated thickening
Heel Fissures
CauseChronic dryness, prolonged standing, obesity, open-back footwear.
AppearanceDeep linear cracks at the heel margin; may bleed or become a portal for infection.
CareEmollients (urea or lactic acid based), gentle debridement, protective footwear.
Suggested Photo
Heel fissure — vertical cracks at the posterior or lateral heel margin
Tinea Pedis (Athlete's foot)
CauseDermatophyte fungal infection thriving in warm, moist environments — sweaty shoes, communal showers.
AppearanceRed, itchy, peeling or macerated skin, classically between the fourth and fifth toes.
CareTopical antifungals, keep feet dry, change socks daily, breathable footwear.
Suggested Photo
Interdigital tinea pedis — maceration and scaling between toes
Diabetic Foot Ulcer
CauseCombination of neuropathy, ischemia, and unrelieved pressure or unrecognized trauma.
AppearanceOpen wound, often painless, slow to heal; classic location is plantar surface beneath the first metatarsal head.
CareWound care per protocol, offloading, glycemic control, urgent referral to wound care or podiatry.
Suggested Photo
Plantar diabetic foot ulcer (use only with patient consent and appropriate framing)
Key Takeaway

The four conditions above account for most of what nurses see at the bedside. Recognizing them quickly — and distinguishing pressure-related from infectious from ischemic — drives the right next step.

Toenail Anatomy

A healthy toenail is a layered keratin structure anchored to the underlying nail bed and protected by the surrounding skin.

Toenail anatomy diagram Top-down view of a great toe showing the nail plate, nail bed visible through the plate, the lunula (whitish half-moon at the base), the cuticle rim, the lateral nail folds, and the free edge at the tip. CUTICLE LUNULA NAIL PLATE visible surface NAIL BED beneath plate LATERAL FOLD FREE EDGE
Top-down view of a great toe showing the visible components of the nail unit

Three components every nurse should recognize

  • Nail plate — the visible, hard, keratinized surface. What patients call "the nail."
  • Nail bed — the vascular tissue under the plate that gives a healthy nail its pink hue and supplies it with nutrients.
  • Cuticle (eponychium) — the protective seal at the proximal nail fold that keeps pathogens out of the matrix.

Common Nail Conditions

Onychomycosis (Fungal nail)
CauseDermatophyte (and less commonly yeast or mold) infection of the nail unit; common in older adults and after chronic tinea pedis.
AppearanceYellow or brown discoloration, thickening, brittleness, subungual debris; great toenail most often affected.
CareConfirm diagnosis (clinical or KOH/culture if needed), conservative debridement, topical or oral antifungal per provider; address concurrent tinea pedis.
Suggested Photo
Healthy nail vs. onychomycotic nail — side-by-side comparison illustrating discoloration and thickening
Ingrown Toenail (Onychocryptosis)
CauseImproper trimming (too short or into the corners), tight footwear, trauma, or anatomic predisposition.
AppearanceErythema, swelling, and tenderness at the lateral nail fold; later stages develop drainage or granulation tissue.
CareWarm soaks, conservative trimming when appropriate, refer to podiatry for procedural management when infection or chronicity is present.
Suggested Photo
Ingrown great toenail with erythema and inflammation of the lateral fold

Best Practices for Skin & Nail Care

What every foot care nurse should do, every visit

  • Inspect the entire foot — top, bottom, between toes, heels — for cuts, ulcers, color or temperature changes, and signs of infection.
  • Teach patients daily foot inspection, gentle washing, and thorough drying (especially between the toes).
  • Recommend moisturizing the heels and dorsum, but not between the toes.
  • Trim nails to follow the natural shape of the nail bed, leaving the corners visible and avoiding cuts below the tip of the toe.
  • Counsel on properly fitting, supportive footwear; replace worn shoes and socks regularly.
  • Refer findings beyond your scope — non-healing wounds, signs of ischemia, infected ingrown nails — to wound care, podiatry, or vascular specialists without delay.
Quick Nursing Tip

Patients with diabetes should never walk barefoot, even at home. Reduced sensation means an unnoticed cut or puncture can become a major wound before the patient realizes anything is wrong.

Case Studies

Case 1 — A Diabetic Patient with a Hidden Foot Wound
Patient

62-year-old male with type 2 diabetes.

Complaint

"My foot feels fine — but my wife says it looks weird."

Findings
  • Small red ulcer beneath the great toe
  • No pain reported (consistent with neuropathy)
  • Cool skin and weak distal pulses (possible vascular compromise)
Best Nursing Approach
  • Assess sensation with monofilament; assess perfusion (pulses, capillary refill, ABI as indicated)
  • Educate patient on daily foot inspection and the role of his wife as a second set of eyes
  • Refer to wound care urgently — diabetic ulcers benefit from early, structured intervention
Case 2 — Older Adult with Thickened, Discolored Nails
Patient

78-year-old woman residing in a long-term care facility.

Complaint

"My toenails are thick, hard, and I don't like how they look."

Findings
  • Yellow, thickened, slightly crumbling toenails on multiple toes
  • No pain, but reports difficulty walking comfortably
Best Nursing Approach
  • Differentiate onychomycosis from age-related nail changes; document findings carefully
  • Trim and file nails conservatively, avoiding injury to the surrounding skin
  • Reinforce hygiene: daily sock changes, breathable footwear, dry between the toes
  • Coordinate with the primary provider on antifungal therapy if a fungal cause is confirmed
Lesson Summary
Key takeaways for nursing practice
  • Foot skin is thicker, sweatier, and more prone to dryness than skin elsewhere — care must reflect that.
  • The four most common skin conditions are calluses, heel fissures, tinea pedis, and diabetic foot ulcers.
  • Healthy nails depend on an intact plate, bed, and cuticle; onychomycosis and ingrown nails are the two pathologies you'll see most.
  • Prevention and early detection — especially in patients with diabetes, vascular disease, or limited mobility — produce the largest patient-outcome gains.

Ready to check your understanding? Take the quick knowledge check for this lesson.

Educational Disclaimer

The information on this website and any communication with RNscrub Foot Care is provided for educational and informational purposes only. It is not a substitute for medical advice, diagnosis, or treatment. Patients are always encouraged to consult with their primary care provider or appropriate specialist for individual clinical decisions.

References

  1. Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 7th ed. Elsevier; 2021.
  2. American Diabetes Association Professional Practice Committee. Standards of Care in Diabetes — 2024 (Section 12). Diabetes Care. 2024;47(Suppl 1).
  3. International Working Group on the Diabetic Foot (IWGDF). IWGDF Guidelines on the Prevention and Management of Diabetes-Related Foot Disease. 2023.
  4. Wound, Ostomy and Continence Nurses Society. Core Curriculum: Wound Management. 3rd ed.
  5. Lipner SR, Scher RK. Onychomycosis: Clinical overview and diagnosis. Journal of the American Academy of Dermatology. 2019;80(4):835–851.
  6. Eba M, Njunda AL, Mouliom RN, et al. Onychomycosis in diabetic patients: a review. BMC Research Notes. 2022;15:1–8.
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