Neurocutaneous system: Is the skin a big eye with deep brain connections?

Traditionally recognised as the body’s largest organ, the skin acts as a protective barrier and primary sensory interface with the external environment. Recent advances in dermatology and neuroscience have revealed a sophisticated neuroendocrine network within the skin, suggesting that the skin’s role extends far beyond mere protection and sensation. In this article, we propose an innovative perspective by conceptualising the skin as a “big eye” in close communication with the central nervous system (CNS). Central to this concept is the idea that all nerve endings in the skin converge into a single extended nerve, like the optic nerve, which we can imagine as a “cutaneous nerve”. This nerve could act as a conduit for the transmission of sensory and emotional information from the skin to the CNS. [...]