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Neurology aNd Special SeNSeS ` neurology—AnAtomy And Physiology Neurology aNd Special SeNSeS ` neurology—AnAtomy And Physiology SecTioN iii 509
Spinal tract anatomy Ascending tracts synapse and then cross.
and functions
trACt FunCtion 1st-order neuron synAPse 1 2nd-order neuron synAPse 2 + ProJeCtions
Ascending tracts
Dorsal column Pressure, Sensory nerve Nucleus Decussates
vibration, ending bypasses gracilis, in medulla
fine touch, pseudounipolar cell nucleus ascends
proprioception body in dorsal root cuneatus contralaterally
ganglion enters (ipsilateral as the medial
spinal cord ascends medulla) lemniscus
ipsilaterally in dorsal
columns VPL (thalamus)
sensory cortex
Spinothalamic tract Lateral: pain, Sensory nerve Ipsilateral gray Decussates
temperature ending (Aδ and C matter (spinal in spinal
Anterior: fibers) bypasses cord) cord as the
crude touch, pseudounipolar cell anterior white
pressure body in dorsal root commissure
ganglion enters ascends
spinal cord contralaterally
Descending tract
Lateral corticospinal Voluntary UMN: cell body in Cell body of LMN: leaves NMJ muscle
tract movement of 1° motor cortex anterior horn spinal cord fibers
contralateral descends ipsilaterally (spinal cord)
limbs (through posterior
limb of internal
capsule and cerebral
peduncle), most fibers
decussate at caudal
medulla (pyramidal
decussation)
descends
contralaterally
FAS1_2019_12-Neurol.indd 509 11/8/19 7:39 AM
