 Palpation
 Bony landmarks
 Dermatomes
Neural assessment

 Epidermis:
Stratified squamous epithelium
Resting on:
 Basement membrane
Resting on:
 Dermis:
Dense irregular connective tissue

 The epidermis is a stratified squamous epithelium.
 It is made up of many layers of cells.
 The stratum germinativum is the deepest layer:
Area of high mitotic activity.

 The stratum corneum is the most superficial layer:
The cells in this layer are dead and keratinized.
 Between the stratum germinativum and the stratum corneum are several transitional layers represented by cells from the stratum germinativum that are transforming into dead, keratinized cells.

 The epidermis is innervated.
 The epidermis is avascular.

 The dermis is the deepest region of the integument.
 The dermis is classified as dense irregular connective tissue
 The dermis has an abundance of collagen fibers
 There may also be some elastic fibers:
Decrease with age.

 The dermis is vascularized.
 Refer to Figure 1 in your course packet.

 Classification into thin and thick skin depends on the structure of the epidermis.
 Layers of epidermis are well-formed in thick skin.
 Layers of epidermis are not as well-formed or thick in thin skin.

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
Thick skin is found only on the palms of the hands and the soles of the feet.
The epidermis of thick skin is 0.4 – 0.6 mm thick
 Thick skin has no hair follicles.

 Thin skin is found over the rest of the body.
 The epidermis of thin skin is 0.075 – 0.150 mm thick.
 Total skin thickness is 0.5 – 3 mm thick.

 Thickest skin found on back (= thin skin)
 Thinnest skin found on eyelids (= thin skin)
 Thicker on extensor surfaces than flexor surfaces.

 Subcutaneous fascia
 Superficial fascia
 Hypodermis
 SubQ

 Consists of loose bundles of collagen and elastic fibers with variably sized aggregations of lipocytes (fat cells)
 May be loosely or tightly attached
 Supports cutaneous nerves and blood vessels

 Synonyms:
Membranous fascia
Investing fascia
 Usually several thin layers of tough collagen material
 Tightly adherent to muscles, bones, tendons, etc.

 Glands.
 Hairs.
 Nails.

 Glands are epithelial structures
 Glands are classified according to the presence or absence of a secretory duct:
Exocrine
Endocrine

 Sudoriferous glands
 Sebaceous glands
 Ceruminous glands
 Mammary glands

 Are long, simple, tubular glands.
 Their method of secretion is merocrine .

 Are holocrine .
 Sebaceous glands are associated with hair follicles.

 Are located in the external auditory canal.
 Secrete ear wax.

 Are modified sweat glands
 Method of secretion is apocrine

 Hairs develop during 3 rd month of gestation.
 The earliest fine embryonic hair = lanugo.
 Lanugo is Shed before birth except around eyebrows, scalp, and eyelids.

 A new downy coat of hair appears a few months after birth.
 This new coat is called vellus.
 Vellus is converted to terminal hair at puberty:
Vellus represents 95% of the hair coverage in males.
Vellus represents 35% of the hair coverage in females.

 Shaft:
Made up of dead cornified epidermal cells.
 Follicle:
Derived from both epidermis and dermis.
 Dermal papilla with matrix.

 Arrector pili muscle.
 Sebaceous glands.
 Hair bulb and connective tissue papilla.

 Anlagen
Active growth:
Scalp hair = 2-3 years
Eyebrow hair = 3-4 months

 Hair follicles are innervated, and hairs serve as sensory receptors.
 Hairs are found everywhere except palms, soles, dorsal distal phalanges, anal and urogenital apertures

 Ungis:
Modified stratum corneum
Flattened
Avascular and not innervated
Travels over a nail bed guided by lateral nail grooves
 Matrix:
Stratum germinativum produces ungis
 Subungis

 Found in deep layers of epidermis
 Derived from nervous system components
 Form:
Melanosomes:
Passed off to keratinocytes (cells of epidermis).
Phagocytized by keratinocytes.

 All individuals produce same number of melanosomes.
 Skin color depends on number of remaining melanosomes.

 Represent tension lines created by orientation of collagen fibers in the dermis of the skin.
 Used by surgeons as guides for incisions:
Incisions normally made parallel to Langer’s lines

 Specific region of skin innervated by a specific spinal cord level.
 Refer in syllabus to figure 3