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Anatomy and Physiology of Motor disorder
- 1. Movement disorders Anatomy and physiology of motor system Shittu LAJ
- 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. Cortex (MI) Internal capsule Brainstem Nucleus ruber Midline Propriospinal interneuron Pyramids Spinal cord a motoneuron Distal limb muscles 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
- 16. Colony Colony Two motoneurons receiving input from cortical cells
- 17. Motor areas Sensory areas Terminations of the corticospinal tract projections of sensory pathways
- 18. Corticospinal tracts Propriospinal interneuron Supraspinal input Ia interneuron Segmental input Renshaw cell Muscle a motoneuron a motoneuron Midline 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. From supraspinal sources InterneuronPresynaptic (Axo-axonic) synapse Muscle Muscle spindel afferent la fibers DRG a motoneuron Monosynaptic stretch reflex
- 21. Stimulus Stimulus Stimulus strength (V) Antidromic motor Motor Orthodromic motor (reflex) EMG A B C 10ms M-wave H-reflex 40 0 2 4 6 8 80 120 M H Hoffman reflex
- 22. Reflexes are modulated from supraspinal sources
- 23. Supraspinal input la interneuron Inhibition on a motoneuron Agonist muscle Antagonist muscle Muscle spindel Stretch reflex arc DRG a motoneuron Reciprocal spinal reflex
- 24. From semicircular canals From uticulus Lateral vestibular nucleus Medial vestibular nucleus Medial vestibular spinal tract Lateral vestibular spinal tract Spinal cord a motoneurons motoneurons Descending vestibular pathways
- 25. Medial system Posture and automatic functions
- 26. Reticulospinal tract la interneuron Muscle Tendon Golgi tendon afferent DRG a Motoneuron (inhibitory input) Tendon reflex
- 27. Reticulospinal pathway la interneuron Extensor muscle Flexsor muscle Flexor reflex afferents a Motoneurona Motoneuron Inhibitory interneuron Excitatory interneuron Flexor reflex
- 28. Interneuron Input A B A a motoneuron Input B Intracellular potential in a motoneuron Input A B A a motoneuron Input B Intracellular potential in a motoneuron Convergence of excitatory inputs Convergence of inhibitory and excitatory inputs
- 29. Muscle lb inhibitory Forelimb afferents la excitatory Decending motor tracts a motoneuron 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. MuscleMuscle la afferents From antagonist muscle spindle From agonist muscle spindle Renshaw FRA Corticospinal tract and interneurons Contralat. Vest. Spinal, FRA etc. Ipsi. vestibular tract Propriospinal input Antagonist a motoneuron Agonist a motoneuron Input to an Ia inhibitory interneuron
- 32. Muscle la Norepinephrine serotonin tract Dorsal reticular spinal tract lb Decending motor tracts Joint receptors Skin receptors a motoneuron Input to an Ib (inhibitory) interneuron
- 35. Cerebellum Corticospinal tract Brain stem motor pathways Interneurons Motor cortex Basal ganglia Thalamus a motor neuron muscle Two descending motor tracts The alpha- motoneuron is the final common pathway
- 36. Fig 5.27B Anatomical localization motor pathways
- 38. Basal ganglia
- 41. SMA/PMC/CM GPi/SNr Putamen Indirect Direct GPe STN Brainstem Spinal Cord VLo VApc/mc CM Direct and indirect pathways
- 42. SMA MI Putamen Globus pallidus STNThalamus Vlo-CM Basal ganglia connect to supplementary motor areas and primary motor cortex SMA: Supplementary motor area STN: Subthalamic nucleus
- 44. Cerebral cortex (MI and SI) Thalamus Cerebellar nucleus Pontine nuclei Red nucleus Cerebellar cortex From spinal cord Rubrospinal tract Involvement of the cerebellum and pontine nuclei
- 45. Overview of motor pathways
- 46. ANATOMICAL LOCATIONS OF THE BASAL GANGLIA
- 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. Cerebellum Corticospinal tract Brain stem motor pathways Interneurons Motor cortex Basal ganglia Thalamus a motor neuron muscle Two descending motor tracts The alpha- motoneuron is the final common pathway
- 56. 80 90 100 110 120 2 3 4 5 6 7 8 9 10 Conditioning-test interval (ms) Effect from spasticity Soleus H-reflex: Effect on Ib inhibition on reflex response Hemiplegic side Normal side
- 57. Inhibitory supraspinal input to motoneuron pool Segmental input Muscle la (from muscle spindles) lb (from Golgi tendon organs) Supraspinal input a motoneuron
- 58. Spinal cord T11-L4 S3-S4 Viceral afferents Uterus Efferent Nociceptors Viceral afferents DRG DRG Viceral afferents Pain fibers Viceral receptors Bladder Visceral afferent innervation in the lower body and motor (efferent) innervation.