Descending tracts have 3 neurons 1st order neurons (UMN) : Cell bodies are in the cerebral cortex & other supra spinal areas 2nd order neurons : Short & situated in the anterior grey column of the spinal cord 3rd order neuron (LMN) : Situated in the anterior grey column & innervate the skeletal muscles through anterior roots of the spinal nerves Cortico-spinal tract :

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2. Branches of the CST
•Branches which are given off early in the descent
return to the cortex to inhibit the activities in adjacent
regions of the cortex
•Branches pass to following areas to keep the sub
cortical areas informed about the cortical motor
activity
1)Caudate & lentiform nuclei
2)Red nuclei
3)Olivary nuclei
4)Reticular formation
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3. Other descending pathways to the spinal cord
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4. Brown sequard syndrome (Hemi section of the spinal cord)
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5. Brown sequard syndrome (Hemi section of the spinal cord)
•Features
1)Ipsilateral LMN paralysis & muscular atrophy in the corresponding part of the
body to the damaged segment of the spinal cord
2)Ipsilateral spastic paralysis below the of the level lesion (γ motor neuron
inhibition is lost)
3)Ipsilateral loss of cutaneous sensation below the of the level lesion
4)Ipsilateral loss of dorsal column sensation below the of the level lesion
5)Contralateral pain, temperature, touch & pressure sensations are lost below the
of the level lesion
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6. Brown sequard syndrome (Hemi section of the spinal cord)
Tracts which are affected
Dorsal column : Ipsilateral
Lateral Spinothalamic tract : Contralateral
Anterior Spinothalamic tract : Contralateral
Anterior Spino cerebellar tract : Contralateral
Posterior Spino cerebellar tract : Ipsilateral
Anterior corticospinal tract : Ipsilateral
Posterior corticospinal tract : Ipsilateral
Autonomic nervous system : Ipsilateral
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