SKIN

1. Describe the structure, appendages of skin

Skin is the largest organ of the body, composed of three layers: Epidermis, Dermis, and Hypodermis.

• Epidermis (outermost layer): stratified squamous epithelium, composed of dead cells
• Dermis (middle layer): loose connective tissue, contains blood vessels, nerves, hair follicles, sebaceous and sweat glands
• Hypodermis (innermost layer): subcutaneous tissue, composed of loose connective tissue and fat cells

Skin appendages include:

• Hair
• Sweat glands
• Sebaceous glands
• Nails
• Arrector pili muscles

2. Mention the functions of skin

The skin serves several functions:

• Protects underlying tissues from external damage and infection
• Regulates body temperature through sweating and dilation/ constriction of blood vessels
• Aids in the production of vitamin D through UV radiation
• Helps in the sensation of touch, pressure, pain, and temperature
• Excretes waste products, such as urea, through sweat
• Assists in the maintenance of fluid balance and blood pressure

3. Describe superficial fascia and its distribution

Superficial fascia, also known as panniculus or subcutaneous tissue, is a layer of loose connective tissue located between the skin and underlying muscles.

• Composed of fat cells, blood vessels, and nerves
• Present in most areas of the body, except for certain bony prominences and joints
• Extends from the skin to the underlying muscles, bones, or other tissues
• Plays a role in maintaining body shape and regulating body temperature

4. Describe deep fascia and its functions

Deep fascia, also known as investing fascia, is a layer of dense connective tissue that surrounds and separates muscles, bones, and other organs.

• Composed of collagen fibers, elastic fibers, and other components
• Provides support, stability, and protection to underlying tissues
• Allows for movement and flexibility of joints
• Facilitates the transmission of forces and stress across the body
• Plays a role in maintaining body posture and movement

Diagram: Skin and Fasciae

Skin Epidermis (outermost layer) Dermis (middle layer) Hypodermis (innermost layer) Superficial Fascia (subcutaneous tissue) Deep Fascia (investing fascia)

Flowchart: Skin Appendages

Hair → Arrector pili muscles → Hair follicles → Sweat glands → Sebaceous glands → Nails

Skin Layers

Superficial Fascia

Deep Fascia

• The superficial fascia is not present in all areas of the body, such as the palms and soles, where it is replaced by a thick layer of skin.
• The deep fascia is continuous with the periosteum, a layer of connective tissue that surrounds bones.