NSCI 2001 Lecture Notes - Lecture 8: Dorsal Root Of Spinal Nerve, Internal Capsule, Sensory System
18 Sep 2018
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Document Summary
Motor system involves descending pathways from cortex down to brainstem known as lateral corticospinal tract (motor limb control) Sensory system = ascending pathways from body to central nervous system. Somatosensory pathways -refers to bodily sensations of touch, pain , and vibration, and temperature. Posterior column-medial lemniscal system_ conveys proprioception (limb or joint position in space), vibration sense and fine touch. Anterolateral pathways - pain, temperature, sense and crude touch. First neuron in both somatosensory pathways is primary sensory neuron that contains specialized receptors in axon terminal to detect stimuli. Receptors are metabotropic- depolarize membrane and generate action potential. Sensory neurons have unique shape-psuedounipolar-one axon and no dendrites. One end innervates sensory organ and other goes to cns. A (delta) and c axons - lightly myleinated or not at all- detect pain and temperature (part of anterolateral pathway) A (alpha) and a (beta)- are large and heavily myelinated and detect proprioception, touch and vibration (part of posterior pathways)
