Nervous system

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This PPT is uploaded by Prof.Dr.R.R.Deshpande.This is prepared by Dr.A.R.Joshi ,Physilogist on Nervous system

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Nervous system

  1. 1. NERVOUS SYSTEM Dr. A. R. Joshi PROFESSOR OF PHYSIOLOGY
  2. 2. Nervous System Central Nervous System • To control voluntary and conscious functions e.g. voluntary movements, appreciation of sensations etc. Autonomic Nervous System • To control in- voluntory functions e.g. beating of heart, movements of intestine etc.
  3. 3. Central Nervous System • Anatomical Division : Brain & twelve pairs of cranial nerves Spinal Cord & thirty one pairs of spinal nerves
  4. 4. Brain • Forebrain - Cerebrum - Thalamus - Hypothalamus • Midbrain • Hindbrain - Pons - Medulla - Cerebellum (Grey matter outside & white matter inside)
  5. 5. Brain… • Blood Supply : 700-800 ml/minute by Circle of Willis. ● Brain is covered by three meninges. ● Lymph is replaced by CSF, present in ventricles of brain & subarachnoid
  6. 6. Spinal Cord • Parts : - Cervical - Thoracic - Lumbar - Sacral Gray matter inside with anterior and posterior roots. White matter outside with anterior, lateral and posterior columns.
  7. 7. Physiological Division • Sensory component Receptor Sensory nerve Ascending tract Thalamus Parietal lobe • Motor Component Frontal lobe Descending tract Anterior horn cell Motor nerve Muscle
  8. 8. Neuron • A functional unit of nervous system • One way conduction in neuron • Cell body is sensory • Axon is motor • Velocity of impulse depends upon - Myelination - Diameter
  9. 9. Synapse • Functional junction between two neurons •Transmission is via Neurotransmitter •Excitatory NTs are Ach, Adr, NA •Inhibitory NTs are Serotonin, GABA, Dopamine, Glycine •(Inhibition can be presynaptic or
  10. 10. Properties of Synapse 1. One way conduction 2. Fatigue 3. Delay 4. Excitation or Inhibition 5. Reciprocal inhibition or cross extensor reflex 6. Reverberation 7. Irradiation
  11. 11. Functions of Spinal cord 1. Reflex action 2. Ascending tracts (Sensory) 3. Descending tracts (Motor) 4. Origin to ANS 5. Inhibitory neurons with different functions
  12. 12. Tracts in Spinal Cord
  13. 13. Tracts in Spinal cord
  14. 14. Dorsal Column Pathways • Tract of Gall (Fasciculus Gracilis) (Carrying fine sensations from lower extremities & trunk) • Tract of Burdach (FasciculusCuneatus) (Carrying fine sensations from upper extremities & chest)
  15. 15. Dorsal Column Pathways… Dorsal root ganglion (1st ordered neuron) ↓ Dorsal column tract in spinal cord on the same side ↓ Nucleus Gracilis & Cuneatus (2nd ordered neuron) (Crossing to opposite side) ↓ Medial lemniscus (Brain Stem) ↓ Thalamus (3rd ordered neuron) ↓ Parietal lobe (Sensory Cortex)
  16. 16. Ascending Tracts (Sensory) 1.Dorsal column tracts (Fine sensations) • Fine touch, • Tactile localization, • Tactile discrimination • Vibration sense, • Sense of stereognosis, • Joint position, Muscle movement
  17. 17. Spinothalamic Pathways 1. Lateral Spinothalamic Tract (Carrying pain & temp. sensation) 2. Ventral Spinothalamic Tract (Carrying crude touch & pressure sensation)
  18. 18. Spinothalamic pathways… Dorsal root ganglion (1st ordered neuron) ↓ SG cells (2nd ordered neuron) in spinal cord ↓ (Crossing to opposite side) ↓ Lateral & Ventral Spinothalamic tract ↓ Thalamus (3rd ordered neuron) ↓ Parietal lobe (Sensory Cortex)
  19. 19. 2. Spinothalamic tracts (Crude sensations) • Crude touch, • Pressure, • Temperature, • Pain • Itch • Sexual sensations
  20. 20. Damage to Sensory Tracts 1. Damage to Dorsal column tract Sensory ataxia Loss of fine sensations Loss of vibration sense Astereognosis on the same side below the level of lesion 2. Damage to Spinothalamic tract Crude sensations lost on opposite side below the level of lesion
  21. 21. Descending Tracts (Motor) 1. Pyramidal tracts: Cortico-spinal fibers: Control of voluntary movements especially skilled movements of distal joints (e.g. writing, painting) and voluntary control of bladder and bowel Corticonuclear fibres: Control of facial movements, eye-ball movements, mastication and speech.
  22. 22. Pyramidal tracts (Cortico- spinal) Motor cortex (Broadman's area 4,6 and 8) ↓ Corona radiata ↓ Internal capsule (Common site of damage) ↓ Crus of Mid brain ↓ Pyramids of Medulla - Crossing on opposite
  23. 23. Hemiplegia •Common site of damage- Internal capsule (damage to Charcot’s artery) •Paralysis on opposite side •Three stages seen •Second stage-typical UMN type of paralysis •Aphasia may be associated •Supra-nuclear facial nerve palsy
  24. 24. Extra-pyramidal Tracts 1. Reticulo-spinal tracts 2. Vestibulo-spinal tracts 3. Rubro-spinal tract 4. Tecto-spinal tract 5. Olivo-spinal tract
  25. 25. Descending Tracts (Motor…) Extra-pyramidal tracts: (Sub cortical origin ) ● Control of gross postural movements of proximal joints like pelvic girdle & shoulder girdle movements ● Control of anti-gravity muscles of lower extremities ● Regulation of muscle tone.
  26. 26. Paraplegia • Paralysis of both lower extremities • Most of the cases are spastic • Three stages are seen • It is UMN type of lesion • Features of complete & incomplete transection may differ.
  27. 27. UMN & LMN concept • UMN : 1st Neuron in motor pathway terminating on LMN e.g.: Pyramidal & extrapyramidal tract neurons • LMN : Last neuron in motor pathway directly supplying muscle e.g. Anterior horn cells & cranial nerve nuclei
  28. 28. UMN Lesion (features) 1. Rigidity or spasticity 2. Hypertonia 3. Deep reflexes are exaggerated 4. No atrophy 5. Positive Babinski’s sign e.g. Hemiplegia or Paraplegia
  29. 29. LMN Lesion (features) 1. Flaccidity 2. Hypotonia 3. All reflexes lost 4. Atrophy seen 5. No Babinski’s sign eg.Poliomyelitis
  30. 30. Spinal cord lesions Causes: • Traumatic e.g. fracture of vertebrae • Infective e.g. tuberculosis • Degenerative e.g. motor neuron disease • Vascular e.g. atherosclerosis • Neoplastic e.g. meningioma
  31. 31. Spinal cord lesions (classification) 1.Lesions of roots: Anterior or posterior root lesions 2.Lesions of cord proper: (a) Complete trans-section (b) Incomplete trans-section including Hemi-section (Brown Sequard syndrome)
  32. 32. Spinal cord Lesions (Stages) 1. Stage of Spinal Shock For 2-3 wks. Picture like LMN lesion 2. Stage of Reflex Activity Can remain life long Picture like UMN lesion 3. Stage of Reflex Failure Complications causing irreversible damage Picture like LMN lesion
  33. 33. Complete transection 1. Paraplegia in Flexion 2. Flexor reflexes return first 3. Mass reflex present Incomplete transection 1. Paraplegia in Extension 2. Extensor reflexes return first 3. Mass reflex absent
  34. 34. Principles of Treatment 1. Treat the basic Cause 2. Maintain the Vital functions 3. Take care of • Nutrition • Bladder • Bowel • Bed sores 4. Start Physiotherapy as early as possible
  35. 35. Functions of Cerebral Cortex Frontal lobe( Motor Functions) 1. Control of Voluntary movements 2. Control of Speech and writing Prefrontal lobe ( Intellectual Functions) 1. Memory and intelligence 2. Thinking and solving of problems 3. Prediction and future planning
  36. 36. Parietal lobe ( Sensory functions) 1. Appreciation of fine sensations 2. Stereognosis, barognosis 3. Appreciation of taste sensation Temporal lobe ( Auditory functions) 1. Appreciation of hearing 2. Behavioral functions like fear and rage Occipital lobe (Visual functions) Appreciation of vision including colors
  37. 37. Functions of Hypothalamus 1. Endocrine control on Pituitary gland 2. Regulation of •Food intake •Thirst •Body temperature •Sex behavior •Circadian rhythms •ANS
  38. 38. Sleep & wakefulness • Temporary state of unconciousness • Neuronal fatigue of ARAS • REM & NREM patterns • Essential for life • Drugs can modify
  39. 39. REM Sleep NREM Sleep 1. Person wakes up in 1. Person goes to sleep this pattern in this pattern 2. Duration less 2. Duration more 3. Eyeballs move 3. No movement 4. Dreams occur 4. Do not occur 5. Difficult to arouse 5. Easy to arouse 6. EEG –Beta pattern 6. EEG –Delta
  40. 40. Functions of Basal Ganglia 1. Regulation of muscle tone 2. Inhibition of motor cortex 3. Timing and scaling of movements 4. Involuntary associative movements 5. Regulation of gross intentional acts
  41. 41. Parkinsonism Deficiency of Dopamine at Corpus Striatum due to damage to Nigro-strial tract Features: 1.Akinesia 2. Rigidity 3. Pill rolling tremors 4.Jerky gait 5. Mask face
  42. 42. Treatment of Parkinsonism 1. Treat the basic cause 2. L-dopa and carbi-dopa group of drugs 3. Anticholinergic drugs 4. Stop Phenothiasines 5. Other drugs like Amantadin, Bromocriptin 6. Transplantation of Adrenal medulla
  43. 43. Functions of Cerebellum 1. Co-ordination of Voluntary movements 2. Timing, planning and scaling of movements 3. Regulation of Muscle tone 4. Regulation of Posture and Equilibrium 5. Regulation of Conjugate eyeball movements 6. Inhibition of Motor cortex
  44. 44. Cerebellar Signs 1. Nystagmus 2. Dysmetria 3. Dysdiadochokinesis 4. Motor ataxia 5. Drunken-man’s gait 6. Pendular knee jerk
  45. 45. Abnormal Gaits 1. Circumduction gait in Hemiplegia 2. Spastic gait in Paraplegia 3. Flaccid gait in Poliomyelitis 4. Drunken-man’s gait in Cerebellar syndrome 5. Jerky gait in Parkinsonism 6. High steppage gait in Dorsal column damage

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