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Motor Nerve Tracts
Tract Name | Function | Origin | Course | Termination | Laterality |
---|---|---|---|---|---|
Corticospinal Tract | Fine movements, Flexor bias | primary motor cortex | post limb IC, cerebral peduncle, long. fibers of pons, pyramids, decussate, spinal cord (90% lat, 10% ant) | spinal cord ventral horn/ventral gray | Contra (lat), Ipsi (med) |
Rubrospinal Tract | gross movements, cervical, flexor bias (arms,shoulders,neck) | red nucleus | dorsal tegmentum w/LCST in spinal cord | spinal cord ventral horn/ventral gray, cervical levels only | Contra (crosses in ventral tegmental decussation) |
Tectospinal Tract | Reflexive movements of head and neck with eyes | superior colliculus | runs ventral to the median longitudinal fasiculus/MVSt/ventromedial spinal cord | spinal cord ventral horn/ventral gray, cervical levels only | Contra (crosses in tegmental decussation |
Lateral Vestibulospinal Tract | balance of trunk, limb girdle, and proximal limbs, extensor bias | lateral vestibular nucleus | not clear, ventromedial spinal cord | ventray gray | Ipsi |
Medial Vestibulospinal Tract | Balance of head and neck, extensor bias | medial vestibular nucleus | runs in the MLF below CN VI, ventromedial spinal cord | ventral gray, cervical and high thoracic | bilateral |
Pontine Reticulospinal Tract | postural/axial movemtn and muscle tone, extensor bias | pontine reticular formation | ventromedial spinal cord | ventral gray | ipsi |
Medullary Reticulospinal Tract | postural/axial movement and muscle tone, flexor bias | meduallary reticular formation | dorsolateral spinal cord (with RST and LCST) | ventral gray | bilateral, with and ipsi bias |
Corticopontine Tract | Brings informaiton from cortex to pons (eventuall to MCP) | primary motor cortex, premotor cortex, primary somatosensory cortex, etc. | ant limb of IC, post limb of IC, cerebral peduncles, pons | pontine nuclei | ipsi |
Corticobulbar Tract | motor input to cranial nerve nuclei, reticular formation and red nuclei | primary motor cortex (face portion) | genu of IC, cerebral peduncle, long. fibers of pons, pyramids | motor nuclei of cranial nerves, red nucleus, reticular formations | All bilateral, except: *Lower face of CN VII and CN XII: contra *Red Nucleus: ipsi *Reticular Formation: contra |