Tone Neurophysiology of Tone wit Insight in Motor System Mechanisms

The presentation gives the neurophysiological rationale of tone and various mechanisms responsible for generation and maintenance for the same. The clinical applications of tine are also addressed.

1. Amitabh Dube, M.D.
Neurophysiology of Tone
Insight In Motor System Mechanisms

2. Muscle Tone
•Resistance of Ms to Stretch
•Mechanisms
•Myotatic: Stretch Reflex
•Non-Myotatic
•Gamma Discharge and Tone
•Stretch Reflex and Tone

3. Motor Unit and Neuronal Pool
•Skeletal Ms
•Motor Unit
•Neuronal Pool

4. Motor Unit and Neuronal Pool
•Skeletal Ms
•Innervated By ??????-Motor Neurone of
Ventral Horn of Spinal Cord & Brain Stem

5. Motor Unit and Neuronal Pool
•Motor Unit
•All Extrafusal Ms Fibres Innervated By
One ??????-Motor Neurone

6. Motor Unit and Neuronal Pool
•Neurone Pool
•All ??????-Motor Neurones Innervating One Ms

7. Proprioceptors: Ms Spindle & GTO
Muscle Spindle Golgi Tendon Organ (GTO)
Fusiform Capsular Structure in Ms Tendon
3-12 Intrafusal Fibres Singular
In Parallel To Extrafusal FibresIn Series To Extrafusal Fibres
Detect Stretch of Ms Detect Change in Ms Tension

8. Ms Spindle Arrangement

10. Ms Spindle Intrafusal Fibres
•Central Region: No Contractile Element
•Several Nuclei
•Nuclear Bag Fibres
•Nuclear Chain Fibres

11. Ms Spindle Intrafusal Fibres
•Nuclear Bag Fibres
•Centrally Clumped Nuclei
•Dynamic Responders
•Nuclear Chain Fibres
•Columnar/Rowed Nuclei
•Static Responder

12. Sensory Innervation of Intrafusal Fibres
•Primary Spindle Afferent
•Secondary Spindle Afferent

13. Sensory Innervation of Intrafusal Fibres
•Primary Spindle Afferent
•Group Ia Afferent
•Annulospiral Ending
•Spirals Round Centre of Nuclear Bag &
Chain Fibres

14. Sensory Innervation of Intrafusal Fibres
•Secondary Spindle Afferent
•Group II Afferent
•Flower Spray Ending
•Mosty Innervate Distal Ends of Nuclear
Chain Fibres

16. Ms Spindle Functions
•Primary Spindle Afferents (Ia)
•Sense Dynamic Change in Ms Length
•Rate of Change of Length

17. Ms Spindle Functions
•Secondary Spindle Afferents (II)
•Sense Static/Steady State Ms Length
Change

18. Ms Spindle Functions
•Contraction of Extrafusal Fibres
•Cessation of Discharge
•Intrafusal Fibres Shrivel

19. ?????? Motor Neurones &
Ms Spindle Sensitivity

21. Ms Spindle Motor Innervation
•Dynamic ?????? Fibre (??????-d/g-d)
•Static ?????? Fibre (g-s)

22. Ms Spindle Motor Innervation
•Dynamic ?????? Fibre (??????-d/g-d)
•Excite Mainly Nuclear Bag Fibres

23. Ms Spindle Motor Innervation
•Static ?????? Fibre (g-s)
•Excites Mainly Nuclear Chain Fibres

24. Ms Spindle
•Nuclear Chain Fibres
•Nuclear Bag Fibres

25. Ms Spindle
•Nuclear Chain Fibres
•Most Responsive To Ms Shortening

26. Ms Spindle
•Nuclear Bag Fibres
•Most Responsive To Ms Lengthening
•Dynamic Vs State Bag

27. Ms Spindle
•Typical Mammalian Ms Spindle
•Nuclear Bag Fibre (Dynamic & Static)
•Variable Nuclear Chain Fibres (@ 5)

28. Ms Spindle Functions
•Stimulation of g-d Fibres
•Stimulation of g-s Fibres
•Stimulation of Fusimotor Fibres (g)

29. Ms Spindle Functions
•Stimulation of g-d Fibres
w?Dynamic Sensitivity of Primary
Afferent

30. Ms Spindle Functions
•Stimulation of g-s Fibres
w?Static Sensitivity of Secondary Afferent

31. Ms Spindle Functions
•Stimulation of Fusimotor Fibres (g)
•Resensitisation of Contracting Intrafusal
Fibres
•Enhance Sensitivity of Ms Length Change
Over Wide Range

32. Gamma Motor System
•Innervation of Intrafusal Ms Fibres

33. Gamma Motor System
•Modulators
•Reticular Formation
•Vestibular System
•Cutaneous Sensory Receptors

34. Gamma Motor System
•Modulators
•Reticular Formation
•Mesencephalic Zone Regulates
Rhythmic Gate

35. Gamma Motor System
•Modulators
•Vestibular System: Lateral Vestibulospinal
Tract
•Facilitates ?????? Motor Neurone Antigravity
Control

36. Gamma Motor System
•Modulators
•Cutaneous Sensory Receptors
•Sensory Afferents Activate ?????? Motor
Neurone

37. Golgi Tendon Organ (GTO)
•Sensitive To Tension Change
•Innervation
•Firing Rate (Sensitive To Tension Changes)

38. Golgi Tendon Organ (GTO)
•Innervation
•Single Group Ib Axon Intertwining
Braided Collagen Fascicles

39. Golgi Tendon Organ (GTO)
•Firing Rate (Sensitive To Changes in Tension)
w?Sensitivity To Stretching
w↑Response With Contraction (Vs Stretch)
wCollagen Stiffer Than Ms Fibre

40. CNS Influence on
Spindle Sensitivity

41. CNS Influence on Spindle Sensitivity
•??????-Motor Innervation To Spindle
•Ia Afferent Discharge Rate

42. CNS Influence on Spindle Sensitivity
•??????-Motor Innervation To Spindle
•Spindle Ends Contract
•Maintains Viability & Functionality of
Spindle During Ms Contraction

43. CNS Influence on Spindle Sensitivity
•??????-Motor Innervation To Spindle
•Operational Over Wide Ms Length Range d/
t ??????-?????? Co-Activation
•Slow Voluntary Movement in Ms Shortening
•↑ Rate of Ia Afferent Discharge

44. CNS Influence on Spindle Sensitivity
•Ia Afferent Discharge Rate
•Sensitive To Rate of Change of Ms Length
During Movement

45. CNS Influence on Spindle Sensitivity
•Ia Afferent Discharge Rate
•Signal/Sensor To
•Irregularities in Movement Trajectory
•Fatigue of Local Group of Ms Fibres

46. Spindles and GTOs
•Ms Contraction Against Load
•?Spindle Activity
•?GTO Activity
•Ms Stretch
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•?GTO Activity Initially

47. Ms Tone
•Supraspinal Control
•Cerebral Cortex
•Suppressor Areas
•2s, 4s, 9s, 24s
•Basal Ganglia
•Supraspinal Control
•Cerebellum
•??????-?????? Linkage
•Reticular Formation

48. Ms Tone
•Hypotonia
•Deafferentation
•?????? Motor Neuron
Damage
•Hypotonia
•Chlorpromazine
•Section Below Vestibular
Nucleus
•Cerebellar Dz in Humans

49. Ms Tone
•Hypertonia
•UMN Lesion
•Basal Ganglia
Disease
•Cerebellar Lesions
•Hypertonia
•Decrebrate Rigidity
•Anxiety

50. UMN Lesions: Causes
•Haemorrhage
•Tumors
•Accidents

51. UMN Lesions: Causes
•Post Operative
•Parasites
•Infections
•Aneurysms

52. UMN Lesions: Signs & Symptoms
•↑ Ms Tone
•Spasticity/Rigidity
•Exaggerated DTRs
•Clonus
•Loss/Decreased Superficial Rx

53. UMN Lesions: Signs & Symptoms
•Positive Babinski’s Sign
•No Voluntary Motor Activity
•Ms Degeneration Not Present
•Absent Reaction Degeneration

54. LMN Lesions: Causes
•Polio Myelitis
•Spinal/Bulbar
•Spinal Cord Lesion

55. LMN Lesions: Causes
•Motor Nerve Damage
•Infections
•Accidents

56. LMN Lesions: Signs & Symptoms
•Ms Tone Decreased/Loss
•Faccid Paralysis
•Absent DTR
•Superficial Rx Lost

57. LMN Lesions: Signs & Symptoms
•Positive Baibinski’s Sign (Vs Sacral Region)
•Ms Degenration Present
•Reaction of Degeneration Present

58. Thank You For
Your Kind Attention