Anatomy Unit - Skin & Fascia Lecture 2

Skin Anatomy

• Skin is the largest organ, forming the body's external surface.
• Composed of two primary layers:
  • Epidermis: Superficial layer, keratinizing stratified squamous epithelium, avascular.
  • Dermis: Deeper layer of connective tissue containing blood vessels, lymph vessels, nerve endings, hair follicles, and glands.

Epidermis

• Nutrients reach the epidermis via diffusion.
• Generally thin except in specific regions where it can be thicker.

Dermis

• Characterized by connective tissue, housing crucial structures.
• Contains sensory and autonomic nerves, blood vessels, and glands (sweat and sebaceous).

Skin Creases and Langer's Lines

• Skin creases occur on joints; the skin is thin and adherent.
• Langer's lines are collagen fibers aligned in specific directions:
  • Longitudinal in limbs.
  • Circumferential in neck and trunk.
• Surgical incisions should follow Langer's lines to minimize scarring.

Pigmentation

• Skin color is influenced by melanin, which shields the germinative layer from UV damage.

Dermatomes

• Areas of skin supplied by single spinal nerve roots.
• Useful for localizing neurologic issues and infections like shingles.

Skin Burns

• Superficial burns: Rapid healing, often does not require grafts.
• Deep burns: Slow healing, frequently necessitate skin grafting.

Appendages of the Skin

• Nails: Composed of a root (embedded), body (exposed), and nail fold. Growth originates from the germinative zone beneath the root.
• Hairs: Found almost everywhere on the body except certain areas like palms and soles. Derived from hair follicles with a supportive hair papilla.
• Sebaceous Glands: Secrete sebum, lubricating skin and hair. Cysts can form from duct obstruction.
• Sweat Glands: Present throughout the body except specific regions.

Clinical Considerations

• Skin infections: Examples include paronychia (infection around nails) and boils (infected hair follicles).
• Example case: Pustular rash following a spa visit likely indicates infection of hair follicles.

Fascia

• Superficial Fascia: Underlies skin; contains fat, blood vessels, nerves, and cutaneous lymphatics. Thinner in some areas (penis, scrotum) and thicker in others (scalp, palms).
  • Functions: Insulates, provides movement facilitation, nourishes cutaneous structures.
• Deep Fascia: Denser than superficial fascia, framing muscle groups and forming structures like intermuscular septa and neurovascular sheaths.
  • Functions: Extra muscle origin points, limits infection spread, maintains muscular compartments in limbs.

Summary of Functions

• Fascia supports muscle function, protects vessels and nerves, and assists in maintaining body integrity during movement and injury.

This quiz explores the anatomy of skin and fascia in detail. You'll examine the layers of skin, skin appendages, and the differences between superficial and deep fascia. The importance of skin creases and dermatomes in surgical anatomy will also be highlighted.