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NAIL STRUCTURE, DISEASES & DISORDERS – (Study Guide)
✨ Why Nail Techs Need to Know This
Understanding nail structure and growth helps identify whether it’s safe to work on a client.
Some nail conditions should not be treated in the salon.
Protect both yourself and clients from disease transmission.
Nail appearance can signal mild to serious health problems requiring a doctor’s care.
💅 Identifying a Normal, Healthy Nail
Firm, flexible, shiny, and slightly pink.
Whitish, translucent plate showing the pink or beige color of the nail bed beneath.
🧬 Natural Nail (ONYX)
A hard, protective plate protecting finger/toe tips.
Appendage of the skin; part of the integumentary system.
Composed mainly of keratin (stronger than in hair or skin).
Made up of several parts:
Nail Bed • Matrix • Nail Plate • Cuticle • Eponychium • Hyponychium • Specialized Ligaments • Nail Folds
🩻 Nail Structure and Functions
| Part | Description & Function |
|---|---|
| Nail Bed | Living skin supporting the nail plate as it grows. Pinkish due to blood vessels. Contains nerves; attached by bed epithelium guiding nail growth. |
| Nail Plate | Hardened keratin plate resting on the bed; ~50 layers of cells; porous (15–25 % water). |
| Free Edge | Extension of the plate beyond the fingertip/toe tip. |
| Matrix | Where nail cells form. Contains nerves, lymph, and blood vessels. The visible whitish half-moon is the lunula. |
| Cuticle | Dead, colorless tissue from the eponychium; seals the gap to protect the matrix. |
| Eponychium | Living skin at the base of the nail plate under the proximal nail fold (PNF). Forms the cuticle. |
| Proximal Nail Fold (PNF) | Skin flap covering the matrix and plate. May be pushed back gently but never cut. |
| Hyponychium | Thickened skin between fingertip and free edge; barrier against microbes. |
| Specialized Ligaments | Fibrous tissue bands anchoring nail bed and matrix to bone. |
| Nail Folds / Grooves | Normal skin folds surrounding the plate; guide nail growth. The lateral nail fold (sidewall) overlaps the nail’s sides. |
🌱 Factors Affecting Nail Growth
Nutrition, exercise, and general health.
Nail shape depends on matrix shape (length = thickness; width/curvature mirror matrix).
Regular manicures, balanced diet, and hydrated cuticles promote healthy growth.
Growth rate: Adults ≈ 1/10–1/8 inch (2.5–3 mm)/month.
Faster in summer and in children.
Slower in elderly.
Toenails grow slower but are thicker (longer matrix).
🧩 Nail Plate Malformation
Shape or thickness may change from matrix injury or infection.
Full nail-plate replacement: 4–6 months (fingers) | 9 months–1 year (toes).
Faster cell production → faster growth; damage → thin plates or grooves.
⚠️ Nail Disorders & Diseases
Nail techs must never diagnose or treat unhealthy nails/skin.
Nail Disorder: unhealthy nail condition (hereditary / injury / disease).
Do not perform services if nails/skin are infected, inflamed, broken, or swollen.
Always use sanitary practices and refer the client to a physician.
🧠 Nail Disorders
1. Eggshell Nail (EGG-shell NAYL)
Description: Thin, white, and flexible nails.
Cause: Poor diet, internal disease, medication, or overfiling.
Salon Care: Handle gently; avoid harsh filing or pressure.
2. Discolored Nail (dis-CUL-er-ed NAYLZ)
Description: Nails with variety of colors (yellow, blue, gray, green, or red).
Cause: Surface staining, systemic disorder, or poor circulation.
Salon Care: Identify cause before treatment; refer to physician if needed.
3. Bruised Nail Bed (BROOZD NAYL-bed)
Description: Dark purplish spots under the nail plate.
Cause: Blood trapped under nail due to injury.
Salon Care: Avoid pressure on the area; polish can camouflage.
4. Beau’s Lines (BOZ LYNZ)
Description: Horizontal depressions across the nail.
Cause: Major illness or injury that temporarily stops nail growth.
Salon Care: Nails will grow out; smooth gently.
5. Hangnail (HANG-nayl)
Description: Split or torn skin near nail plate.
Cause: Dryness or cutting living skin.
Salon Care: Trim carefully; apply cuticle oil; never pull.
6. Infected Finger (in-FEK-ted FING-er)
Description: Red, swollen, painful, pus-filled area around nail.
Cause: Bacterial infection.
Salon Care: Do not perform service; refer to doctor.
7. Leukonychia (loo-koh-NIK-ee-ah)
Description: White spots on nail plate.
Cause: Minor injury to nail matrix.
Salon Care: Spots will grow out with nail.
8. Melanonychia (mel-uh-nuh-NIK-ee-uh)
Description: Dark band or pigmentation down the nail.
Cause: Increased melanin; common in darker skin tones.
Salon Care: Normal in many clients; refer to doctor if new or changing.
9. Nail Psoriasis (NAYL suh-RY-uh-sis)
Description: Surface pitting, roughness, and discoloration.
Cause: Psoriasis affecting the nail bed.
Salon Care: No cure; perform gently, avoid harsh chemicals.
10. Nail Pterygium (NAYL tuh-RIJ-ee-um)
Description: Skin stretched over the nail plate.
Cause: Injury or disease of the matrix.
Salon Care: Never push or cut; refer to physician.
11. Onychophagy (ah-nih-KOH-fah-jee)
Description: Bitten nails.
Cause: Habit or stress.
Salon Care: Regular manicures and polish can help improve appearance.
12. Onychorrhexis (ah-nick-oh-REK-sis)
Description: Split or brittle nails with lengthwise ridges.
Cause: Injury, harsh chemicals, or aging.
Salon Care: Keep nails moisturized; avoid metal tools.
13. Pincer Nail (PIN-ser NAYL)
Description: Nail edges curve deeply inward (trumpet-shaped).
Cause: Heredity or tight shoes.
Salon Care: Trim carefully; do not forcefully cut edges.
14. Plicatured Nail (plik-uh-CHORD NAYL)
Description: Folded nail with 90° curve along edges.
Cause: Injury or heredity.
Salon Care: Avoid aggressive filing; gently smooth edges.
15. Ridges (RIDJD NAYL)
Description: Lengthwise grooves in the nail plate.
Cause: Aging or uneven growth.
Salon Care: Buff lightly; use ridge filler before polish.
16. Splinter Hemorrhage (SPLIN-tur HEM-er-ij)
Description: Thin red or brown lines under the nail plate.
Cause: Trauma or injury to nail bed capillaries.
Salon Care: Will grow out; avoid pressure on area.
🩺 NAIL DISEASES
1. Pseudomonas aeruginosa
Cause: Rapidly growing contagious bacteria.
Signs: Green-yellow spot that darkens to brown/black as it worsens.
Notes: Occurs between natural nail and artificial nail.
Action: Medical referral required.
2. Pyogenic Granuloma
Cause: Severe inflammation of the nail, often from injury or infection.
Signs: Red tissue lump grows from nail bed to nail plate.
Action: Medical referral required.
3. Tinea Pedis (Athlete’s Foot)
Cause: Fungal infection.
Signs: Red, itchy patches between toes or on feet; may have blisters or peeling.
Spread: Contagious – can spread by dirty tools/equipment.
Action: Medical referral required.
4. Onycholysis
Definition: Separation of nail plate and bed.
Cause: Injury, allergic reaction, or infection.
Signs: Lifting at free edge; white appearance.
Action: Keep area clean/dry; medical referral if infected.
5. Onychocryptosis
Common Name: Ingrown nail.
Cause: Nail grows into skin (hands or feet).
Signs: Pain, redness, swelling at nail edges.
Action: Do not remove ingrown portion; medical referral.
6. Onychomadesis
Definition: Separation and falling off of nail from matrix.
Cause: Injury or severe infection.
Action: Medical referral required.
7. Onychomycosis
Cause: Fungal infection of nail plate.
Signs: Thick, discolored, or crumbly nails.
Action: Medical referral required.
8. Onychia
Definition: Inflammation of nail matrix with pus or shedding.
Cause: Bacterial infection or injury.
Signs: Redness, swelling, tenderness.
Action: Medical referral required.
9. Paronychia
Definition: Bacterial inflammation of tissue around the nail.
Signs: Redness, swelling, pain, pus.
Cause: Often from prolonged water exposure or harsh detergents.
Action: Medical referral required.
🧤 Safety Tips to Prevent Infection & Injury
Wear nitrile gloves.
Disinfect all metal implements.
Dispose of single-use items.
Use a clean towel for each client.
Keep Safety Data Sheets (SDS) for every product—know usage, handling, and disposal.
🧫 Nail Infections & Sanitation
Proper cleaning/disinfection reduces cross-contamination.
Mix disinfectants per label directions; change daily.
Follow correct dilution ratios (e.g., 1 oz disinfectant : 32 oz water).
Any signs of infection—redness, pain, swelling, pus, broken skin—mean no service.
Broken or cut skin lets germs enter and cause infection.