Tracts and Tract Lesions Flashcards Preview

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Flashcards in Tracts and Tract Lesions Deck (22):
1

Dorsal Column (Medial Lemniscus) Pathway

- Touch, pressure, proprioception, 2 pt. discrimination, vibration - DRG to Nucleus Cuneatus (UL) or Gracilus (LL) via fasciculus cuneatusor fasciculus gracilus -> medial lemniscus to VPL -> VPL to primarysomatosensory cortex - Crosses in caudal medulla as internal arcuate fibers

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Spinothalamic Pathway

- Pain and temperature - DRG to substantia gelatinosa via Lissauer’s tract -> cross in white anteriorcommissure -> spinothalamic pathway to VPL -> VPL to Somatosensorycortex

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Trigeminal (touch, pressure, proprioception)

- DRG -> Trigeminal ganglion -> primary/main/principal nucleus oftrigeminal -> cross in pons -> ascend via trigeminothalamic tract to VPM -> VPM to primary somatosensory cortex

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Lateral Corticospinal Tract

UMN (1st orderneuron) = in Motor Cortex - Axons travel via the Internal Capsulethrough the Cerebral Peduncle, Pons, andPyramids - ~85% of fibers cross in theDecussation of the Pyramids LMN (2nd order neuron) = in Ventral Horn of spinal cord - Output to skeletal muscles

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Anterior Corticospinal Tracts

- Motor cortex -> cervical/upper thoracic spinal cord -bilateral for axial musculature control – posture -does NOT cross at the pyramidal decussation, but at level in spinal cord.

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Anterior Spinocerebellar Tract

- Information about intended movement from lower extremities...inform about activity of inhibitory interneurons 1st Order Neuron = DRG- Fibers travel via Fasiculus Gracilis to... 2nd Order Neuron = Spinal Border Cells- Fibers cross in Anterior White Commissure, ascend via theAnterior Spinocerebellar Tract (via anterior lateral funiculus), cross again in the brainstem, and pass through the Superior Cerebellar Peduncle (SCP) to the Cerebellum

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Dorsal (Posterior) Spinocerebellar Tract

- Status of individual muscles in the trunk & LOWER limb 1st Order Neuron = DRG - Fibers travel via Fasiculus Gracilisto... 2nd Order Neuron = Clarke’sNucleus (Column) (T1-L2) - Fibers travel rostrally via the DorsalSpinocerebellar Tract (via lateralfuniculus) through the Inferior Cerebellar Peduncle (ICP) and into theCerebellum

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Cuneocerebellar Tract

- Status of individual muscles in the UPPER limb 1st Order Neuron = DRG - Fibers travel via Fasciculus Cuneatus to... 2nd Order Neuron = Lateral(external) Cuneate Nucleus - Fibers travel rostrally via theCuneocerebellar Tract and throughthe Inferior Cerebellar Peduncle(ICP) to the Cerebellum

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Medial (Pontine) Reticulospinal Tracta

- Enhances antigravity reflexes Originates in Pons (nucleus reticularis pontis oralis and nucleus reticularis pontis caudalis) No decussation, remains ipsilateral Terminates on All levels of Sp. C. Lamina VIII (VII, IX) -Fas Vol. or cortically induced movements. ↑muscle tone =actions on γMNs

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Lateral (Medullary) Reticulospinal Tract

- Liberates antigravity muscles from reflex originates in the Medulla (nucleus reticularis gigantocellularis Partial decussation in the Medulla Terminates on All levels of Sp. C. Lamina VII (VI, VIII, IX) - Inhibits voluntary & cortically induced movements. ↓muscle tone by further inhibiting muscle spindle activity =actions on γMNs

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Medial reticulospinal fibers (Pontoreticulospinal fibers)

Excitatory to extensor motor neurons and to neurons innervating axial musculature Some fibers may inhibit flexor motor neurons

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Lateral reticulospinal fibers (Bulboreticulospinal fibers)

Inhibitory to extensor motor neurons and neurons innervating muscles of neck and back Some fibers also may excite flexor motor neurons

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Medial Lemniscus (Dorsal Column) Pathway

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Spinothalamic Pathway

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Trigeminal (touch, pressure, proprioception from face)
 

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Trigeminal (pain and temperature from face)
 

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Lateral Corticospinal Tract

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Anterior Corticospinal Tract

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Medial Lemniscus (Dorsal Column) Pathway

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Substantia Gelatinosa

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Spinothalamic Tract 

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Corticospinal Tract