Good Afternoon!!

1. Good Afternoon!! Michael Lipton, M.D.

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

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

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

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

9. Pierre Paul Broca (1824-1880) From an engraving after a portrait (1867) by LaFosse.

10. Lateral Corticospinal Tract • Most direct pathway • …but 50% of axons ® cerebellum via pons • Voluntary motor control • fine movement/distal muscles • Monosynaptic to hand • gross movement • synapse on spinal interneurons >50% of CS axons

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

12. Brain Imaging Transverse (Axial) Imaging

13. 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

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

15. Functional Imaging (fMRI) Roland What was this person doing?

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

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

25. Essential Points • List the descending pathways • Lateral Corticospinal • Anterior Corticospinal • Rubrospinal • Tectospinal • Vestibulospinal • Reticulospinal • [Corticostriatal] Direct cortex effect Indirect cortex effect

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

27. 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

28. Essential Points • Identify sites of decussation • Lateral Corticospinal • Anterior Corticospinal • Rubrospinal • Tectospinal • Vestibulospinal • Reticulospinal Medullary Pyramid Not Applicable Midbrain Tegmentum Midbrain Not Applicable

29. Sagittal Imaging: Identify regions

31. Brain Imaging Transverse (Axial) Imaging

32. Coronal Imaging TENT