Touch, Localization of
Ability to determine the more or less precise area of the body that is the recipient of mechanical stimulation.
Touch is mediated by essentially four different systems. A more crude or primitive sense of touch is carried by the anterolateral system for sensory input for the most part at the cervical level or below (essentially the trunk and the four extremities), whereas the spinal tract and nucleus of the fifth cranial nerve carries comparable information from the face. The lemniscal system or posterior column provides more precise tactile information for the body, while the chief or principal nucleus of cranial nerve V serves the same function for the face. All four systems eventually project to the somatosensory cortex of the postcentral gyrus, which, like the motor system is topographically organized, allowing for sensory localization beyond that defined by the individual dermatomes. However, because the lemniscal system and principal nucleus of cranial...
References and Readings
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