Ascending tracts of spinal cord



Situation Tract Origin Course Termination Function
Anterior white funiculus 1.Anterior spinothalamic  tract Chief sensory cells Crossing in spinal cord, forms spinal lemniscus Ventral posterolateral nucleus of thalamus Crude touch sensation
Lateral white funiculus 2. Lateral spinothalamic tract Substantia gelatinosa Crossing in spinal cord, forms spinal lemniscus Ventral posterolateral nucleus of thalamus Pain and temperature sensations
  3. Ventral spino-cerebellar tract Marginal cells Crossing in spinal cord Anterior lobe of cerebellum Subconscious kinesthetic sensations
  4. Dorsal spino-cerebellar tract Clarke's column cells Uncrossed fibers Anterior lobe of cerebellum Subconscious kinesthetic sensations
  Spinotectal tract Chief sensory cells Crossing in spinal cord Superior colliculus Concerned with spinovisual  reflex
  6.Fasciculus dorsolateralis Posterior nerve root ganglion Component of lateral spinothalamic tract Substantia gelatinosa Pain and temperature sensations
  7. Spinoreticular tract Intermedio- lateral cells Crossed and uncrossed fibers Reticular  formation of brainstem Consciousness and awareness
  8.Spino-olivary tract Not specific Uncrossed  fibers Olivary nucleus Proprioception
  9.Spino-vesti- bular tract Not specific Crossed and uncrossed fibers Lateral vestibular nucleus Proprioception
Posterior white funiculus   10.Fasciculus gracilis Posterior nerve root ganglia Uncrossed fibers. No synapse in spinal cord Nucleus gracilis in medulla Tactile sensation.  Tactile localization.  Tactile discrimination. Vibratory sensation. Conscious kinesthetic sensation. Stereognosis.
  11.Fasciculus cuneatus Posterior nerve root ganglia Uncrossed fibers. No synapse in spinal cord Nucleus cuneatus  in medulla    

Descending tracts of spinal cord

 

Tract

Situation Origin Course Function

Pyramidal tracts

1. Anterior corticospinal tract Anterior white funiculus Betz cells and other cells of motor area Uncrossed fibers

1. Control of voluntary

 movements.

2. Upper motor

Neurons functions

 

 

2. Lateral corticospinal tract Lateral white funiculus Betz cells and other cells of motor area Crossed fibers

Extra-pyramidal tracts

1. Medial longitudinal fasciculus Anterior white fasciculus Vestibular nucleus.  Reticular formation.  Superior colliculus and  cells of Cajal Uncrossed fibers.  Extend up to upper cervical segments 1. Coordination of reflex ocular move- ments. 2. Integration of movements of eyes and neck.
2. Anterior vestibulo- spinal tract Anterior white funiculus Medial vestibular nucleus Uncrossed fibers. Extend up to upper  thoracic segments 1. Maintenance of muscle tone and posture. 2. Maintenance of position of head and body during acceleration
  3. Lateral vestibule- spinal tract Lateral white funiculus Lateral vestibular  nucleus Mostly un- crossed.  Extend to all segments    
  4. Reticulo- spinal tract Lateral white fasciculus Reticular formation of pons and medulla Mostly un- crossed.  Extend upto thoracic segments 1. Coordination of  voluntary and reflex movements. 2. Control of muscle tone. 3. Control of respi- ration and blood vessels
  5. Tectospi- nal tract Anterior white funiculus Superior colliculus Crossed fibers. Extend up to lower cervical segments. Control of movement of head in response to visual and auditory impulses
  6. Rubro- spinal tract Lateral white funiculus Red nucleus Crossed fibers. Extend up to thoracic seg- ments. Facilitatory influence on flexor muscle tone
  7. Olivo- spinal tract Lateral white funiculus Inferior olivary  nucleus Mostly crossed. Extent—not clear. Control of movements due to proprioception

Termination — Fibers of all the tracts terminate in motor neurons situated in the anterior gray horn of spinal cord

Sensory pathways


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