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Good Afternoon!!

Good Afternoon!!. Objectives. Identify major cortical inputs to the motor pathways List the descending pathways differentiating characteristics Trace the lateral corticospinal tract Identify sites of decussation. Lateral Systems Corticospinal Lateral Rubrospinal. Medial systems

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Good Afternoon!!

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  1. Good Afternoon!!

  2. Objectives • Identify major cortical inputs to the motor pathways • List the descending pathways • differentiating characteristics • Trace the lateral corticospinal tract • Identify sites of decussation

  3. Lateral Systems Corticospinal Lateral Rubrospinal Medial systems Corticospinal Anterior Reticulospinal Tectospinal Vestibulospinal Descending Pathways a a

  4. Direct Systems Corticospinal Lateral Anterior Indirect Systems Rubrospinal Reticulospinal Tectospinal Vestibulospinal Interstitiospinal (??) Descending Pathways Motor Cortex Input ? Input ?

  5. Lateral systems • Fine voluntary movement • Distal muscles • Medial systems • Postural and reflex movement • Proximal and axial muscles

  6. Motor Cortex • M1 = Primary • precentral gyrus • SMA = supplementary • anteromedial • Premotor Area • Anterolateral • Cingulate Motor • ??

  7. SMA Premotor Primary Motor

  8. Lateral Corticospinal Tract • Most direct pathway • …but 50% of axons ® cerebellum via pons • Voluntary motor control • fine movement/distal muscles • monosynaptic • gross movement • synapse on spinal interneurons • “double decussating” >50% of CS axons

  9. Lateral Corticospinal Tract • M1 (and premotor cortex) • Centrum Semiovale • Corona Radiata • Internal Capsule -- posterior limb • Cerebral Peduncle • Pontine Tegmentum • Medullary Pyramid

  10. Sagittal Imaging

  11. Central (Rolandic) Sulcus • Its more posterior than you’d expect • Pearl:follow the superior frontal sulcus back to the precentral sulcus • Remember:All anatomy is variable Roland

  12. Primary Motor & Sensory Cortex • Precentral Sulcus • Primary Motor • Postcentral Sulcus • Primary Sensory Motor Sensory Roland

  13. Functional Imaging (fMRI) Roland

  14. Brain Imaging Transverse (Axial) Imaging

  15. Coronal Imaging TENT

  16. Wallerian Degeneration • Motor Cortex Injury • Degeneration of first order motor neurons • Outlines the corticospinal tract

  17. Precentral Gyrus

  18. Corona Radiata

  19. Pontine Tegmentum

  20. Medullary Pyramid

  21. Essential Points • Identify major cortical inputs to the motor pathways • M1=primary motor cortex • Premotor Cortex • SMA=supplementary motor area • Cingulate Motor Area

  22. Essential Points • List the descending pathways • Lateral Corticospinal • Anterior Corticospinal • Rubrospinal • Tectospinal • Vestibulospinal • Reticulospinal Direct Indirect

  23. Essential Points • Differences • Lateral Corticospinal • Rubrospinal • Anterior Corticospinal • Tectospinal • Vestibulospinal • Reticulospinal Distal muscles Fine movement Proximal and axial muscles Gross and postural movement

  24. Essential Points • Trace the lateral corticospinal tract • M1 (and premotor cortex) • Centrum Semiovale • Corona Radiata • Internal Capsule -- posterior limb • Cerebral Peduncle • Pontine Tegmentum • Medullary Pyramid

  25. Essential Points + Double Decussating • Identify sites of decussation • Lateral Corticospinal • Anterior Corticalspinal • Rubrospinal • Tectospinal • Vestibulospinal • Reticulospinal Medullary Pyramid Not Applicable Midbrain Tegmentum Midbrain Not Applicable

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