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A cutaneous receptor is a sensory receptor found in the skin that provides information about temperature, touch (including vibration and pain), spatial orientation,pressure (stretching or squeezing), and metabolic circumstances (including those induced by external chemical substances).
Hyperalgesia (/ ˌ h aɪ p ər æ l ˈ dʒ iː z i ə / or /-s i ə /; hyper from Greek ὑπέρ (huper) 'over' + -algesia from Greek ἄλγος (algos) 'pain') is an abnormally increased sensitivity to pain, which may be caused by damage to nociceptors or peripheral nerves and can cause hypersensitivity to stimulus.
Their acute sensitivity provides the neural basis for reading Braille text. Because of their superficial location in the dermis, these corpuscles are particularly sensitive to touch and vibrations, but for the same reasons, they are limited in their detection because they can only signal that something is touching the skin. [12]
Aδ fibers are characterized by thin axons and thin myelin sheaths, and are either D-hair receptors or nociceptive neurons. Aδ fibers conduct at a rate of up to 25 m/s. D-hair receptors have large receptive fields and very low mechanical thresholds, and have been shown to be the most sensitive of known cutaneous mechanoreceptors.
The intensity of pain reported is consistently reduced in response to touch. [5] [6] [7] This occurs whether the touch is at the same time as the pain, or even if the touch occurs before the pain. [8] Touch also reduces the activation of cortical areas that respond to painful stimuli. [9]
Cutaneous dysesthesia is characterized by discomfort or pain from touch to the skin by normal stimuli, including clothing. The unpleasantness can range from a mild tingling to blunt, incapacitating pain. [citation needed] Scalp dysesthesia is characterized by pain or burning sensations on or under the surface of the cranial skin. Scalp ...
Pacinian corpuscles are rapidly adapting phasic receptors that detect gross pressure changes and vibrations in the skin. [6] Pacinian corpuscles have a large receptive field on the skin's surface with an especially sensitive center. [7] The corpuscles are especially sensitive to vibrations, which they can sense even centimeters away. [7]
Merkel cells, also known as Merkel–Ranvier cells or tactile epithelial cells, are oval-shaped mechanoreceptors essential for light touch sensation and found in the skin of vertebrates. They are abundant in highly sensitive skin like that of the fingertips in humans, and make synaptic contacts with somatosensory afferent nerve fibers.