Mucocutaneous boundary

A mucocutaneous zone is a region of the body in which mucosa transitions to skin. Mucocutaneous zones occur in animals, at the body orifices.

In humans, mucocutaneous zones are found at the lips, nostrils, conjunctivae, urethra, vagina (in females), foreskin (in males), and anus.

At a mucocutaneous zone, epithelium transitions to epidermis, lamina propria transitions to dermis, and smooth muscle transitions to skeletal muscle. A mucocutaneous zone is often the site of an arterial anastomosis, a watershed area of venous and lymphatic drainage, and sensory (but not motor) nerve overlap.

Winkelmann (1959) reported the mucocutaneous boundary is a "specific erogenous zone with rete ridges where the nerve endings rise closer to the surface."

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