ANP 1106 Lecture Notes - Lecture 15: Postcentral Gyrus, Spinothalamic Tract, Posterior Grey Column

• School: University of Ottawa
• Department: Anatomy and Physiology
• Course: ANP 1106
• Professor: Joanne Savory

Document Summary

The three main levels of neural integration in the somatosensory system are: Receptor level: the sensory receptors (ie. muscle spindle, free nerve endings) Perceptual level: neuronal circuits in the cerebral cortex. Second order sensory neurons receive synapses from primary sensory neurons, and immedi- ately cross the midline to project to the appropriate nucleus of the thalamus. Second order neu- rons for pain are in the spinal cord grey matter, with second order neurons for fine touch are in the brain stem nuclei (dorsal column nuclei in the medulla). Afferent pain pathways differ from afferent non-pain sensory pathways. Provides conscious sensations of poorly localized touch, pressure, pain, and temperature. Axons of first-order neurons enter the spinal cord and synapse on second-order neurons within the posterior grey horns. Axons of these interneurons cross to the opposite side of the spinal cord before ascending to the thalamus. The third-order neuron synapses in the primary sensory cortex.