INTEGUMENT

Surface Anatomy Palpation Bony landmarks Dermatomes Neural assessment

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

Epidermis 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.

Epidermis 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.

Epidermis The epidermis is innervated. The epidermis is avascular.

Dermis 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.

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

Thick Skin vs. Thin Skin 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.

Thick Skin 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 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.

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

Superficial Fascia: Synonyms Subcutaneous fascia Superficial fascia Hypodermis SubQ

Superficial Fascia 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

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

Cutaneous Derivatives Glands. Hairs. Nails.

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

Epidermal Glands Sudoriferous glands Sebaceous glands Ceruminous glands Mammary glands

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

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

Ceruminous Glands Are located in the external auditory canal. Secrete ear wax.

Mammary Glands Are modified sweat glands Method of secretion is apocrine

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

Hairs 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.

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

Parts of a Hair Arrector pili muscle. Sebaceous glands. Hair bulb and connective tissue papilla.

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

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

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

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

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

Langer’s Lines 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

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