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Unformatted text preview: Chapter 14 Somatosensory system: Cutaneous Propriception Kienesthesis SKIN: Heaviest organ Largest surface area Layers: Epidermis dead skin cells Dermis has the mechanoreceptors Mechanoreceptors: On the epidermis (merkel/messian corpuscle) On the dermis (ruffini/ paccinan corpuscle) On the EP I DER M IS On the DER M IS Merkel 3-10hz Messiner corpuscle Ruffini 15-50hz Paccini corpuscle 10- 400hz Continuous response On and off Continuous response On and off Slow adapting Fast adapting Slow adapting Fast adapting Responds to fine details Responds to hand grip LOW FREQUENCY! Stretching High frequency vibrations LEARN HOW T HEY LOOK! PATHWAYS: Peripheral nerves Dorsal route spinal cord (two pathways) ventrolateral nucleus (synapse) somatosensory receiving area ( parietal lobe) Found in the spinal chord Medial L eminscal lathway S pinothalamic pathway Long Small Position and touch Temperature and pain Mylinated Unmylinated (i.e to sense pain) These crossover at the ventrolateral nucleus These cross over at the spinal cord V IMP : you must notice that unlike the visual system here both pathways go to the opposite side of the brain, i.e. both pathways cross-over. In the visual system only the nasal fibers crossover to the contralateral eye!...
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This note was uploaded on 04/20/2011 for the course PSYC 212 taught by Professor Shahin during the Fall '11 term at McGill.
- Fall '11