Motor System

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Motor System

  1. 1. Motor System Nabeel Kouka, MD, DO, MBA www.brain101.info
  2. 2. Effectors MOTOR SYSTEM Skeletal Muscle SOMATIC MOTOR SYSTEM Smooth Muscle AUTONOMIC MOTOR SYSTEM Glands (sympathetic and Parasympathetic) Elements of Motor System
  3. 3. Somatic Motor System
  4. 4. Autonomic Motor System sympathetic response
  5. 5. Somatic Motor System Upper Motor Neuron Lower Motor Neuron Skeletal Muscle Auxiliary Motor Pathways motor nerve pyramidal tract reflex arc descending pathways from brain stem
  6. 6. LOWER MOTOR NEURON Spinal Cord Anterior Horn Cell (Lamina IX) -------- spinal n. Brain Stem General Somatic Efferent (GSE) Nuclei Hypoglossal Nucleus -------------------- XII Abducens Nucleus ------------------------ VI Trochlear Nucleus ------------------------- IV Oculomotor Nucleus ---------------------- III Special Visceral Efferent (SVE) Nuclei Ambiguus Nucleus ----------------------- IX, X, XI Facial (Motor) Nucleus ------------------- VII Trigeminal Motor Nucleus -------------- V
  7. 7. AHC Anterior Horn Cell - Lower Motor Neuron -
  8. 8. Lower Motor Neuron cell body: anterior horn axon: anterior root, spinal nerve axon terminal: neuromuscular junction Effector: skeletal muscle
  9. 9. <ul><li>Spinal Cord </li></ul><ul><li>anterior root: </li></ul><ul><li>- motor </li></ul><ul><li>posterior root: </li></ul><ul><li>- sensory </li></ul><ul><li>Law of </li></ul><ul><li>Bell-Magendie </li></ul>
  10. 10. Lower Motor Neuron N M
  11. 11. Neuromuscular Junction (Myoneural Junction, Motor End Plate) NMJ M N
  12. 12. <ul><li>muscle weakness </li></ul><ul><li>which is greatly </li></ul><ul><li>increased by exertion or </li></ul><ul><li>repeated contraction </li></ul><ul><li>autoimmune disease </li></ul><ul><li>with autoantibodies </li></ul><ul><li>against Ach receptor </li></ul><ul><li>maybe fatal if untreated </li></ul><ul><li>by respiratory paralysis </li></ul><ul><li>treated with </li></ul><ul><li>AchT inhibitors , </li></ul><ul><li>thymectomy, and </li></ul><ul><li>corticosteroids </li></ul>Defects in Neuromuscular Transmission before treatment after treatment MYASTHENIA GRAVIS
  13. 13. EFFECTOR Skeletal Muscle
  14. 15. Upper Motor Neuron Pyramidal Tract corticospinal tract corticobulbar tract
  15. 16. Albertus Magnus (1206-1280) Phrenology of Gall (1758-1828) and Spurzheim (1776-1832)
  16. 17. Motor Homunculus
  17. 18. Somatic Motor System Upper Motor Neuron UMN Final Common Pathway Lower Motor Neuron LMN Skeletal Muscle Descending Brain Stem Pathways motor nerve pyramidal tract reflex arc VOLUNTARY CONTROL AUTOMATIC MOTOR CONTROL
  18. 19. Corticospinal Tract Origin: Cerebral Cortex Brodmann Area 4 (Primary Motor Area, M I) Brodmann Area 6 (Premotor Area, PM ) Brodmann Area 3,1,2 (Primary Somesthetic Area, S I) Brodmann Area 5 (Anterior Portion of Sup. Parietal Lobule) Corona Radiata lnternal Capsule, Posterior Limb Crus Cerebri, Middle Portion Longitudinal Pontine Fiber Pyramid - pyramidal decussation Corticospinal Tract - Lateral and Anterior Termination: Spinal Gray (Rexed IV-IX) Upper Motor Neuron Pyramidal Tract
  19. 20. Upper Motor Neuron Pyramidal Tract 1. corona radiata 2. internal capsule, posterior limb 3. crus cerebri 4. longitudinal pontine fiber 5. pyramid 6. pyramid decussation 7. lateral corticospinal tract 8. anterior corticospinal tract
  20. 21. Upper Motor Neuron Pyramidal Tract 1. corona radiata 2. internal capsule 3. crus cerebri 4. pontine longitudinal fiber 5. pyramid 6. pyramid decussation 7. lateral corticospinal tract 8. anterior corticospinal tract
  21. 22. Upper Motor Neuron Corticospinal Tract
  22. 23. <ul><li>Corticospinal </li></ul><ul><li>Tract </li></ul><ul><li>completion of </li></ul><ul><li>myelination in </li></ul><ul><li>2 nd year of life </li></ul><ul><li>time of </li></ul><ul><li>standing and </li></ul><ul><li>walking </li></ul>
  23. 24. Corticospinal tract myelination
  24. 25. Upper Motor Neuron Pyramidal Tract Corticobulbar Tract - Corticofugal fibers projecting to, and terminating in the portions of lower brainstem - Termination: 1) motor nuclei (upper motor neuron pathway) hypoglossal, ambiguus, facial motor, trigeminal motor, abducens, trochlear and oculomotor nucleus 2) sensory relay nuclei nuclei gracilis and cuneatus, trigeminal sensory nucleus, solitary tract nucleus 3) reticular formation (corticoreticular fiber)
  25. 26. Corticobulbar Tract (UMN Pathway) - Corticofugal fibers projecting to, cranial motor nuclei GSE - hypoglossal (XII), abducens (VI), trochlear (IV) and oculomotor (III) nucleus SVE - ambiguus (IX, X, XI), facial motor (VII), trigeminal motor (V) nucleus - largely bilateral laryngeal, pharyngeal, palatal and upper facial muscles of mastication and extraocular muscles - unilateral lower facial musculature (facial palsy) SCM and trapezius (uncrossed) --- spinal accessory - Pseudobulbar Palsy --- syndrome of bilateral UMN lesion Upper Motor Neuron Pyramidal Tract
  26. 27. Upper Motor Neuron vs Lower Motor Neuron Syndrome LMN syndrome UMN Syndrome Type of Paralysis Flaccid Paralysis Spastic Paresis Atrophy Severe Atrophy No (Disuse) Atrophy Deep Tendon Reflex Absent DTR Increase Pathological Reflex Absent Positive Babinski Sign Superficial Reflex Present Absent Fasciculation and Could be Absent Fibrillation Present
  27. 28. UMN and LMN Syndrome - Paralysis
  28. 29. Upper Motor Neuron Syndrome Spasticity - Increased resistance to passive movement in antigravity muscle (flexor in arm, extensor in leg) Clasp Knife Phenomenon - Sign of Upper Motor Neuron Syndrome, especially internal capsule lesion cf. Rigidity - increased muscle tone, no increased DTR Cogwheel Phenomenon - symptom of basal ganglia or cerebellar lesion
  29. 30. LMN Syndrome - Muscular Atrophy
  30. 31. Dorsiflexion of great toe and Fanning of other toes associated with plantar flexion on mechanical stimulation of the outer edge of the sole of the foot. (Extensor Plantar Response) UMN syndrome BABINSKI SIGN
  31. 32. UMN Syndrome – Increased Deep Tendon Reflex
  32. 33.  Increased DTR is characteristic sign of UMN syndrome  Monosynaptic reflex  Patellar tendon stretch receptor to anterior horn cell  Quadriceps contraction Deep Tendon Reflex (Knee Jerk)
  33. 34. LMN Syndrome – Fasciculation and Fibrillation Electromyography (EMG) Hypersensitivity to circulating acetylcholine
  34. 35. LMN syndrome and UMN Syndrome <ul><li>Predominantly Motor Syndromes </li></ul><ul><li>Poliomyelitis (Infantile Paralysis) </li></ul><ul><li>- viral infection of lower motor neuron </li></ul><ul><li>- LMN syndrome at the level of lesion </li></ul><ul><li>Amyotrophic Lateral Sclerosis (ALS) </li></ul><ul><li>- combined LMN and UMN lesion </li></ul><ul><li>- LMN syndrome at the level of lesion </li></ul><ul><li>- UMN syndrome below the level of lesion </li></ul><ul><li>- Lou Gehrig’s disease in USA </li></ul>
  35. 36. Spinal Cord Syndrome Amyotrophic Lateral Sclerosis 1. corticospinal tract (UMN) 2. lower motor neuron (LMN)
  36. 37. Spinal cord of amyotrophic lateral sclerosis * * * * * *
  37. 38. Motor Syndrome Amyotrophic Lateral Sclerosis (ALS) Lou Gherig’s Disease Lou &quot;The Iron Horse&quot; Gehrig (1903-41) 3.40, 2131(1925-39), 23 GSH, 147 RBI avg.
  38. 39. Spinal Cord Syndrome Amyotrophic Lateral Sclerosis (ALS) Lou Gehrig’s Disease Stephen Hawking (1946- ) British Physicist, A Brief History of Time
  39. 40. Facial Palsy (Bell’s Palsy) Lower Motor Neuron Syndrome Triple W Sign - Wrinkle, Wink, Whistle
  40. 41. Central Type Facial Palsy Upper Motor Neuron Syndrome facial motor nucleus neurons supplying forehead muscle Bilateral Corticobulbar Tract
  41. 42. <ul><li>Inability to properly </li></ul><ul><li>execute a learned </li></ul><ul><li>skilled movement </li></ul><ul><li>Absence of paralysis </li></ul><ul><li>Caused by lesions in </li></ul><ul><li>1. Premotor Area </li></ul><ul><li>2. Corpus Callosum </li></ul><ul><li>3. Parietal somesthetic </li></ul><ul><li>association area </li></ul><ul><li>(storage of body </li></ul><ul><li>image) </li></ul>APRAXIA – Cortical Lesion
  42. 43. Somatic Motor System Upper Motor Neuron UMN Final Common Pathway Lower Motor Neuron LMN Skeletal Muscle Descending Brain Stem Pathways motor nerve pyramidal tract reflex arc VOLUNTARY CONTROL AUTOMATIC MOTOR CONTROL
  43. 44. Pyramidal Tract and Associated Circuits lower motor neuron CEREBELLUM BASAL GANGLIA Upper Motor Neuron UMN Lower Motor Neuron LMN
  44. 45. Cerebellum
  45. 46. Basal Ganglia
  46. 47. Somatic Motor System Upper Motor Neuron UMN Final Common Pathway Lower Motor Neuron LMN Skeletal Muscle Descending Brain Stem Pathways motor nerve pyramidal tract reflex arc VOLUNTARY CONTROL AUTOMATIC MOTOR CONTROL
  47. 48. AUTOMATIC MOTOR CONTROL Spinal Cord Level: - Spinal Reflex : Monosynaptic & Polysynaptic Brain Stem Level: Reticulospinal Pathways Lateral and Medial Reticulospinal Tract Ventromedial Pathways Tectospinal Tract Vestibulospinal Tract MLF (medial longitudinal fasciculus) Posterolateral Pathways Rubrospinal Tract
  48. 49. Dorsolateral and Ventromedial Motor Pathways Dorsolateral (Motor) Pathway Rubrospinal Tract Ventromedial (Motor) Pathway Tectospinal Tract Vestibulospinal Tract MLF (Medial Longitudinal Fasciculus) - interstitiospinal tract Brain Stem Automatic Motor Control
  49. 50. ventromedial pathway dorsolateral pathway Descending Motor Tracts from Brain Stem Automatic Motor Control
  50. 51. AUTONOMIC MOTOR SYSTEM Sympathetic Division Parasympathetic Division
  51. 52. AUTONOMIC MOTOR SYSTEM Postganglionic Neuron Preganglionic Neuron Smooth Muscle & Gland HYPOTHALAMUS Preganglionic Fiber Postganglionic fiber Descending Autonomic Pathway Ach Ach & NE
  52. 53. AUTONOMIC MOTOR SYSTEM Intramural ganglia Paravertebral ganglia Cranial ganglia Prevertebral ganglia Postganglionic Neuron Preganglionic Neuron Parasympathetic Sympathetic Effectors: Smooth Muscle & Gland HYPOTHALAMUS Descending Autonomic Pathway Ach Ach Ach NE
  53. 54. AUTONOMIC MOTOR SYSTEM Spinal Cord - Intermediolateral Cell Column Sympathetic: T 1 -L 3 Parasympathetic: S 2 -S 4 Brain Stem Parasympathetic (GVE) Dorsal Motor Nucleus of Vagus -------- X Inferior Salivatory Nucleus -------------- IX Superior Salivatory Nucleus ------------ VII Edinger-Westphal Nucleus--------------- III
  54. 55. Parasympathetic Sympathetic
  55. 56. Sympathetic Parasympathetic Cardiovascular system blood vessels none to skeletal muscle vasodilation to skin and viscera vasoconstriction Heart rate, force of contraction increases decreases Respiratory system diameter of air passages increases decreases respiratory rate increases decreases Eye dilate pupil constrict pupil accommodation distance vision near vision Sweat gland increased secretion none Adrenal gland secretes E, NE none
  56. 57. Sympathetic Parasympathetic Digestive system general level of activity decreases increases sphincters constrict dilate secretory glands inhibit stimulate salivary gland stimulate simulate serous secretion watery secretion Urinary system kidneys decreases urine increases urine urinary bladder relaxes tenses sphincter constricts relaxes Male reproductive system increases erection glandular secretion and ejaculation
  57. 58. <ul><li>Sympathetic Response </li></ul><ul><li>- fight of flight reaction </li></ul><ul><li>increases blood supply </li></ul><ul><li>to skeletal muscle </li></ul><ul><li>increases heart rate </li></ul><ul><li>increases diameter of </li></ul><ul><li>air passages </li></ul><ul><li>increases rate of respiration </li></ul><ul><li>dilate pupil </li></ul><ul><li>secrets epinephrine and </li></ul><ul><li>norepinephrine </li></ul><ul><li>decreases blood to viscera </li></ul><ul><li>constricts bladder sphincter </li></ul><ul><li>increases sweat production </li></ul><ul><li>constrict arrector pili muscle </li></ul>
  58. 59. <ul><li>Parasympathetic </li></ul><ul><li>Response </li></ul><ul><li>- energy conservation for </li></ul><ul><li>emergency situation </li></ul><ul><li>increases general activity of </li></ul><ul><li>digestive system </li></ul><ul><li>increases secretion of </li></ul><ul><li>digestive glands </li></ul><ul><li>increases urine production </li></ul><ul><li>and relaxes sphincter </li></ul><ul><li>erection </li></ul><ul><li>decreases diameter of </li></ul><ul><li>air passages </li></ul><ul><li>decreases respiratory rate </li></ul><ul><li>constricts pupil </li></ul>

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