Thick Skin HISTOLOGY (Slide Identification – OSPE Points)

 

Thick Skin

Thick Skin (Glabrous Skin) — Anatomy, Histology & OSPE Guide

Definition: Thick skin is hairless skin found on the palms and soles, specialized for grip and resistance to friction.

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📍 Anatomical Location

1. Palmar surface of hands

2. Plantar surface of feet

3. Most prominent on fingertips and heel

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🔬 HISTOLOGY (Slide Identification – OSPE Points)

✅ How to Identify Thick Skin on a Slide

1. Very thick epidermis

2. Five distinct epidermal layers

3. Prominent stratum lucidum

4. Very thick stratum corneum

5. No hair follicles

6. No sebaceous glands

7. Numerous eccrine sweat glands

8. Deep rete ridges and dermal papillae

9. Pacinian corpuscles in deep dermis/hypodermis

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🧫 Epidermal Layers (From Deep to Superficial)

1. Stratum basale

• Single layer of cuboidal/columnar cells
• Mitotically active
• Contains melanocytes & Merkel cells

1. 2 Stratum spinosum

• Several layers
• Prominent desmosomes (“spiny” appearance)
• Langerhans cells present

1. 3 Stratum granulosum

• 3–5 layers
• Keratohyalin granules
• Lamellar bodies (water barrier)

1. 4 Stratum lucidum (ONLY in thick skin)

• Clear eosinophilic layer
• Dead keratinocytes
• Contains eleidin

1. 5 Stratum corneum

• Extremely thick
• Flattened anucleate keratinized cells

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🧬 Dermis

Papillary Layer

• Loose connective tissue
• Dermal papillae (fingerprints)
• Capillary loops
• Meissner corpuscles (light touch)

Reticular Layer

• Dense irregular connective tissue
• Collagen type I
• Sweat glands
• Pacinian corpuscles (pressure/vibration)

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🧪 Hypodermis

• Adipose tissue
• Large blood vessels
• Pacinian corpuscles

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🧠 Physiology

1️⃣ Protection

• Thick keratin resists mechanical stress
• Prevents water loss

2️⃣ Grip Function

• Friction ridges increase traction
• Improve tactile sensitivity

3️⃣ Thermoregulation

• Numerous eccrine sweat glands
• Evaporative cooling

4️⃣ Sensory Function

• Meissner corpuscles → fine touch
• Pacinian corpuscles → vibration

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⚠️ Pathology (Important for Exams)

1. Hyperkeratosis

• Excess keratin layer
• Seen in calluses

2. Psoriasis

• Rapid epidermal turnover
• Parakeratosis
• Thickened stratum corneum

3. Eczema (Dermatitis)

• Spongiosis
• Inflammatory infiltrate

4. Palmoplantar Keratoderma

• Marked thickening of palms/soles

5. Blister Formation

• Separation between epidermal layers
• Due to friction

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🏥 Clinical Significance

• IV access avoided in thick skin
• Important in dermatological diagnosis
• Sweat gland disorders (hyperhidrosis)
• Diabetic neuropathy testing (sole sensation)
• Forensic science → fingerprints

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📌 OSPE Short Note Format (Quick Revision)

Slide ID: Thick skin
Key Features:

• 5 layers of epidermis
• Prominent stratum lucidum
• Thick stratum corneum
• No hair follicles
• No sebaceous glands
• Numerous eccrine sweat glands
• Deep rete ridges

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🔎 Differences: Thick vs Thin Skin

Feature	Thick Skin	Thin Skin
Location	Palms/Soles	Rest of body
Stratum lucidum	Present	Absent
Hair follicles	Absent	Present
Sebaceous glands	Absent	Present
Stratum corneum	Very thick	Thin

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🎓 Research Importance

• Wound healing studies
• Barrier function analysis
• Keratinocyte differentiation research
• Transdermal drug delivery studies
• Stem cell research (basal layer)

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