Ascending/Sensory Pathways and Tracts:
After sensory nerves enter spinal cord segregated into nerve bundles (tracts) in white matter. Transmit impulses to various regions of the brain via pathways consisting of two or three neurons
1) Dorsal column pathways
• fasciculus cuneatus and fasciculus gracilis:
• located posteriorly
• transmits sensory impulses from general sensory receptors of skin (vibratory and discriminative touch) and proprioceptors
• cuneatus – transmits from upper limb; gracilis from lower
• involved in discriminative touch, vibration and conscious proprioception
2) Spinothalamic pathways
• lateral spinothalamic
• located laterally in spinal cord
• transmits impulse associated with pain and temperature to opposite side of brain somatosensory cortex
• anterior spinothalamic
• located anteriorly
• transmits impulses associated with crude/light touch and pressure to opposite side of brain somatosensory cortex
3) Spinocerebellar pathways
• posterior spinocerebellar
• transmits impulses from trunk and lower limb proprioceptors on one side of the body to same side of cerebellum
• subconscious muscle/tendon proprioception
• anterior spinocerebellar
• transmits impulses from the trunk and lower limb on the same side of the body to the cerebellum
• subconscious muscle/tendon proprioception
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