ABSTRACT
This chapter focuses on sensory inputs arising from the skin surface—cutaneous sensibility—and describes the neurobiological processes that enable the skin to be sensitive. The primary sensory modality subserving the body senses is collectively described as the somatosensory system and comprises all the peripheral afferent nerve fibers and specialized receptors subserving proprioceptive and cutaneous sensitivity. Skin sensations are multimodal and are classically described as subserving the three submodalities of touch, temperature, and pain. In sensitive skin conditions and some painful neuropathic states, sympathetic nerves play a role in exacerbating inflammation and irritation. One hypothesis is that pleasant touch stimulates opioid and cannabinoid receptors on the peripheral nerve fibers and that electrical signal is decoded in areas of the brain such as the insular cortex, which is associated with pleasure. The discriminative touch system crosses in the medulla, where the spinal cord joins the brain; the pain system crosses at the point of entry into the spinal cord.
