Skin Blood Supply: Vascular Anatomy & Thermoregulation

The skin's blood supply originates from musculocutaneous and direct cutaneous arteries that penetrate the deep fascia and form a rich subdermal (subcutaneous) plexus in the hypodermis.

Vascular Layers

1. Deep plexus (subdermal): At fascia-fat interface. Supplies fat, hair follicles, deep glands, and feeds the superficial plexus.
2. Superficial plexus (subpapillary): At dermis-subcutis border. Capillary loops project into dermal papillae → nourish epidermis (avascular).

Specialized Structures

• Arteriovenous anastomoses (glomus bodies): Direct artery-to-vein shunts in palms, soles, nail beds, ears, nose. Critical for thermoregulation—open to dissipate heat, close to conserve.
• Venous plexus: Drains into deep system; acts as capacitance reservoir.

Functions

• Nutrient/O₂ delivery, waste removal
• Thermoregulation: Vasodilation (heat loss) vs. vasoconstriction (heat conservation)
• Inflammatory response (leukocyte trafficking)
• Wound healing (angiogenesis)

Cutaneous circulation receives ~5% of cardiac output at rest; can increase 10-fold during heat stress.