1. CHAPTER V Movement disorders Part I: Anatomy and physiology of motor system

2. Motor systems Motor systems are complex and include sophisticated control systems the purpose of which is to serve locomotion, posture and work.

3. Several feedback systems monitor muscle activity The length of muscles and the strength of contractions are monitored by: –Input from proprioceptive receptors in muscles, joints and tendons –Local feedback from motor nerves (Renshaw inhibition)

4. Posture Monitored by proprioceptors, vestibular system vision

5. Causes of movement disorders More or less anatomically specific neural degeneration Injuries (trauma, strokes, surgery, etc) Chemicals (alcohol, drugs) Inflammations and infections (viral) Tumors Genetic Neural plasticity Genetic Idiopathic

6. Motor disorders Lack of function Inadequate function Hyperactivity

7. Disorders of motor systems Hypokinesia Hyperkinesia –Spasticity Ataxia Gait and balance disturbances

8. Two different descending motor pathways: Lateral system –Fine movements Medial system –Posture etc.

9. Lateral system

10. Medial system

12. Motor pathways The motoneurons (alpha motoneurons) are the final common pathways

13. The alpha-motoneurons (common final pathway) receive many inputs Some are facilitating and some are inhibitory

14. Motor pathways

15. Somatotopic organization of the motor cortex

16. Two motoneurons receiving input from cortical cells

17. Motor areas Sensory areas Terminations of the corticospinal tract projections of sensory pathways

18. Renshaw inhibition Fibers of the corticospinal tract terminate on motoneurons or interneurons

19. Extensive processing of motor command occurs in the spinal cord (and brainstem) Spinal reflexes play an important role in all motor functions Some functions such as walking is programmed in the spinal cord

20. Monosynaptic stretch reflex

21. Hoffman reflex

22. Reflexes are modulated from supraspinal sources

23. Reciprocal spinal reflex

24. Descending vestibular pathways

25. Medial system Posture and automatic functions

26. Tendon reflex

27. Flexor reflex

28. Convergence of excitatory inputs Convergence of inhibitory and excitatory inputs

29. Input to propriospinal neurons of the forelimb of the cat

30. From Rosler Fig 2B Magnetic stimulation of motor cortex in an awake individual

31. Input to an Ia inhibitory interneuron

32. Input to an Ib (inhibitory) interneuron

33. BASAL GANGLIA Extrapyramidal system Pyramidal system

35. Two descending motor tracts The alpha- motoneuron is the final common pathway

36. Anatomical localization motor pathways

38. Basal ganglia

39. Parkinson’s disease

40. Huntington’s disease

41. Direct and indirect pathways

42. Basal ganglia connect to supplementary motor areas and primary motor cortex SMA: Supplementary motor area STN: Subthalamic nucleus

43. Involvement of the cerebellum

44. Involvement of the cerebellum and pontine nuclei

45. Overview of motor pathways

46. ANATOMICAL LOCATIONS OF THE BASAL GANGLIA

47. Middle cerebral artery

48. BASAL GANGLIA

50. ANATOMICAL LOCATION OF THE CAUDATE NUCLEUS

51. Somatotopic organization of the motor cortex

52. Cortical motor areas The central sulcus divides motor and sensory areas

53. Overview of motor pathways

54. Two descending motor tracts The alpha- motoneuron is the final common pathway

56. Effect from spasticity Soleus H-reflex: Effect on Ib inhibition on reflex response Hemiplegic side Normal side

57. Inhibitory supraspinal input to motoneuron pool

58. Visceral afferent innervation in the lower body and motor (efferent) innervation.