The cutaneous vascular supply has a primary function: thermoregulation. The secondary function is nutrition of the skin and appendages. The arrangement of blood vessels permits rapid modification of blood flow according to the required loss or conservation of heat.

Three interconnected networks are recognized in the skin:

1. The subpapillary plexus, running along the papillary layer of the dermis.

2. The cutaneous plexus, observed at the boundary of the papillary and reticular layers of the dermis.

3. The hypodermic or subcutaneous plexus, present in the hypodermis or subcutaneous adipose tissue.

The subpapillary plexus gives rise to single loops of capillaries within each dermal papilla. Venous blood from the subpapillary plexus drains into veins of the cutaneous plexus.

Branches of the hypodermic and cutaneous plexuses nourish the adipose tissue of the hypodermis, the sweat glands, and the deeper segment of the hair follicle.

Arteriovenous anastomoses (shunts) between the arterial and venous circulation bypass the capillary network. They are common in the reticular and hypodermic regions of the extremities (hands, feet, ears, lips, nose) and play a role in thermoregulation of the body. The vascular shunts, under autonomic vasomotor control, restrict flow through the superficial plexuses to reduce heat loss, ensuring deep cutaneous blood circulation. In some areas of the body (for example, the face), cutaneous blood circulation is also affected by an emotional state.

A special form of arteriovenous shunt is the glomus apparatus. It is found in the dermis of the fingertips, under the fingernails and toes and is involved in temperature regulation. The glomus consists of an endothelial-lined channel surrounded by cuboidal pericyte-like glomus cells and a rich nerve supply. Glomus tumors are benign, usually very small (about 1 cm in diameter) red-blue nodules, associated with sensitivity to cold and severe intermittent focal pain. Surgical excision provides immediate pain relief.

Lymphatic vessels are blind endothelial cell-lined spaces located below the papillary layer of the dermis, collecting interstitial fluid for return to the blood circulation. They also transport Langerhans cells to regional lymph nodes.