Ascending Neural Pathways Flashcards
which ascending tracts carries info from the lower body extremities?
fasciculus gracilis
which ascending tracts carries info from the upper body extremities?
fasciculus cuneatus
which tracts carry proprioceptive info from muscle spindles (dorsal) and golgi organs (ventral)?
dorsal and ventral spinocerebellar
what tract carries pain?
spinothalamic
what does fasciculus gracilis tract carry?
info from lower limb extremities
what does fasciculus cuneatus carry?
info from upper limb extremities
what do dorsal and ventral spinocerebellar tracts carry?
proprioceptive info from muscle spindles (dorsal) and golgi organs (ventral)
what does the spinothalamic tract carry?
principally pain
what are the 3 principal ascending tract systems in the spinal cord?
- dorsal colum-medial lemniscal pathway
- spinothalamic pathway
- spinocerebellar pathway
what pattern do conscious sensory pathways generally follow?
- first order neuron terminates in spinal cord or brainstem
- second order neuron projects to thalamus
- third order neuron projects to primary sensory cortex
what is the dorsal column-medial lemniscal pathway for?
mechanical stimuli:
- conscious proprioception
- discriminative touch
- vibration
- presssure
what sort of fibres is the axon of the medial lemniscal pathway composed of?
large diameter, fast Aβ fibres
in the medial lemniscal pathway, 1st order neurons ascend ipsilaterally in dorsal columns known as?
- fasciculus gracilis (enters up to T6)
- fasciculus cuneatus (enters above T6)
what happens after gracile and cuneatus nuclei synapse in brainstem with 2nd order neurons?
- they decussate (cross over)
- form the medial lemniscus
- project to VPL (ventral posterolateral lobe) of thalamus
what do pathological processes in the medial lemniscal pathway cause?
gait ataxia - brain is deprived of info about position of feet
what do lesions on the cervical cord cause?
upper extremity ataxia
what is gait ataxia?
abnormal, uncoordinated movements due to brain deprived of info about position of feet
what causes upper extremity ataxia?
lesions on cervical cord
what does dorsal column disease cause?
paraesthesia in distal parts of extremities