Ascending/Sensory Pathways and Tracts

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