Sensory System

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Sensory System

  1. 1. Sensory System Nabeel Kouka, MD, DO, MBA www.brain101.info
  2. 2. environment animal organism Nervous system sensory neuron stimulus reaction effector Inter- neuron receptor Motor neuron Nervous System stimulus and reaction
  3. 3. Sensory System  Modality of Sensation  Receptor  Sensory Tract Primary Neuron Secondary Neuron Tertiary Neuron Termination
  4. 4. Modality of Sensation  General Sensation, Special Sensation vision, hearing, equilibrium, smell, taste  Exteroception, Interoception, Proprioception conscious vs. unconscious proprioception position sensation, kinesthesia  Touch, Pain, Temperature Sensation discriminative vs. light touch sensation fast vs. slow pain
  5. 5. Receptors  Peripheral Nerve Ending  Receptor Neuron Olfactory Neuron of Olfactory Epithelium  Specialized Receptor Cell Merkel cell of Epdermis Taste (Gustatory, Clear) Cell of Taste Bud Photoreceptor cells of Retina Hair cells of Inner Ear
  6. 6. Receptor: Peripheral Nerve Endings <ul><li> R eceptor Neurons of Craniospinal Ganglion </li></ul><ul><ul><li>Pseudounipolar neurons of dorsal root ganglia </li></ul></ul><ul><ul><li>Trigeminal (semilunar, Gasserian ganglion), </li></ul></ul><ul><ul><li>geniculate (VII), superior IX, superior X ganglia (GSA) </li></ul></ul><ul><ul><li>Geniculate (VII), inferior IX, inferior X ganglia (VA) </li></ul></ul><ul><li>Morphological Classification </li></ul><ul><ul><li>Free nerve endings </li></ul></ul><ul><ul><li>Expanded tip endings </li></ul></ul><ul><ul><li>Encapsulated endings ----- CT envestment </li></ul></ul>
  7. 7. Receptors  Free Nerve Endings - Nerve endings without special structural organization - pain and temperature receptor  Expanded Tip Endings - Merkel’s Touch Corpuscle Merkel cells in basal layer of epidermis - Type I Hair cells of Vestibular Labyrinth
  8. 8. Receptors  Encapsulated Endings - Meissner’s Corpuscle - Pacinian Corpuscle (Corpuscle of Vater-Pacini) - Genital Corpuscle - Ruffini’s Ending - End Bulb of Krause - Golgi tendon organ: Proprioceptor
  9. 9. <ul><li>Receptor </li></ul><ul><li>Endings </li></ul><ul><li>Free nerve </li></ul><ul><li>ending </li></ul><ul><li>Expanded tip </li></ul><ul><li>ending </li></ul><ul><li>Encapsulated </li></ul><ul><li>ending </li></ul>
  10. 10. <ul><li>Both receptor and effector </li></ul><ul><li>Structure </li></ul><ul><li>1. Capsule </li></ul><ul><li>2. Intrafusal Muscle Fibers </li></ul><ul><li>- Nuclear Bag Fiber </li></ul><ul><li>- Nuclear Chain Fiber </li></ul><ul><li>3. Receptor and Effector Nerve Endings </li></ul><ul><li>- Afferent Ending </li></ul><ul><li>- Efferent Ending </li></ul>Neuromuscular Spindle
  11. 11. <ul><li>INTRAFUSAL MUSCLE FIBERS </li></ul><ul><li>(1) Nuclear Bag Fiber </li></ul><ul><li>- 1-4 / each spindle </li></ul><ul><li>- longer and thicker than nuclear chain fiber </li></ul><ul><li>- large central aggregation of nucleus in </li></ul><ul><li> equatorial region </li></ul><ul><li>(2) Nuclear Chain Fiber </li></ul><ul><li>- many fibers / spindle </li></ul><ul><li>- smaller and thinner than nuclear bag fiber </li></ul><ul><li>- central row of nucleus in equatorial region </li></ul>Neuromuscular (Muscle) Spindle
  12. 12. <ul><li>INNERVATION </li></ul><ul><li>Afferent Fibers: Proprioceptors </li></ul><ul><li>(1) Primary (Annulospiral) Endings </li></ul><ul><li>- Group Ia (12-20  m in diameter) afferents </li></ul><ul><li>- terminate in both NB and NC fibers </li></ul><ul><li>- wound around the central equatorial region </li></ul><ul><li>(2) Secondary (Flower-Spray) Endings </li></ul><ul><li>- group II (6-8  m in diameter) afferent </li></ul><ul><li>- terminates predominantly in nuclear chain fiber </li></ul><ul><li>- terminates around juxtaequatorial region </li></ul>Neuromuscular (Muscle) Spindle
  13. 13. <ul><li>INNERVATION </li></ul><ul><li>Efferent Fibers </li></ul><ul><li>Gamma (  ) Motor Fiber </li></ul><ul><li>- terminates in small motor end plates </li></ul><ul><li> of the non-nucleated (striated) /region </li></ul><ul><li> of both intrafusal muscle fibers </li></ul>Neuromuscular (Muscle) Spindle
  14. 15. Sensory System General Sensation
  15. 16. Pathways for General Sensation Touch & Proprioception from body Posterior White Colum-Medial Lemniscal Pathway Pain & Temperature from body Spinothalamic Tract cf. Spinoreticular or Spinoreticulothalamic Tract General Sensation from Face Trigeminothalamic Tracts Sensory System General Sensation
  16. 17. Modality: Discriminative Touch Sensation (include Vibration) and Conscious Proprioception (Position Sensation, Kinesthesia) from body Receptor: Most receptors except free nerve endings 1st Neuron: Dorsal Root Ganglion Posterior White Column 2nd Neuron: Dorsal Column Nuclei (Nucleus Gracilis et Cuneatus) Internal Arcuate Fiber - Lemniscal Decussation - Medial Lemniscus 3rd Neuron: Thalamus (VPLc) Internal Capsule ----- Corona Radiata Termination: Primary Somesthetic Area (S I) Posterior White Colum-Medial Lemniscal Pathway
  17. 18. DRG: Dorsal Root Ganglion 1. Posterior White Column A. Nucleus gracilis B. Nucleus cuneatus 2. Medial Lemniscus 3. Corona Radiata C. Thalamus (VPLc) D. Cerebral Cortex (S I) Posterior White Column-Medial Lemniscal Pathway DRG D
  18. 19. Peripheral Nerve
  19. 20. DRG (dorsal root ganglion) neuron pseudounipolar cell peripheral process central process telodendron cell body in DRG
  20. 21. NG: Nucleus Gracilis NC: Nucleus Cuneatus IAF: internal arcuate fiber LD: lemniscal decussation ML: medial lemniscus PWC-ML Pathway Secondary Neuron
  21. 22. Thalamus Ventral Posteromedial (VPL) Nucleus
  22. 23. Sensory Homunculus
  23. 24. Pain Pathway Spinothalamic Tract Anteromedial System
  24. 25. Pain Pathway <ul><li>Peripheral </li></ul><ul><li>chemical </li></ul><ul><li>mediators of </li></ul><ul><li>pain and </li></ul><ul><li>hyperalgesia </li></ul><ul><li>histamine </li></ul><ul><li>bradykinin </li></ul><ul><li>prostaglandins </li></ul><ul><li>potassium (K + ) </li></ul>
  25. 26. Modality: Pain & Temperature Sensation, Light Touch from body Receptor: Free Nerve Ending 1st Neuron: Dorsal Root Ganglion 2nd Neuron: Dorsal Horn (Lamina I, IV, V) Anterior White Commissure Spinothalamic Tract (Spinal Lemniscus) 3rd Neuron: Thalamus (VPLc & CL) Internal Capsule ----- Corona Radiata Termination: Primary Somesthetic Area (S I) Spinothalamic Tract
  26. 27. Spinothalamic Tract
  27. 28. Modality: Pain & Temperature Sensation, Light Touch from body Receptor: Free Nerve Ending 1st Neuron: Dorsal Root Ganglion 2nd Neuron: Dorsal Horn (Lamina I, IV, V) Anterior White Commissure Spinothalamic Tract (Spinal Lemniscus) 3rd Neuron: Reticular Formation 4rd Neuron: Thalamus (CL, Sm, POm) Internal Capsule ----- Corona Radiata Termination: Diffuse Cerebral Cotex Spinoreticulothalamic Tract (Paleospinothalamic Tract)
  28. 29. Spinothalamic Tract spinothalamic tract anterior white commissure posterior root decussation - contralateral loss of pain and temperature sensation below the level of lesion
  29. 30. DRG: Dorsal Root Ganglion A. Spinal Dorsal Horn B. Reticular Formation 1. Neospinothalamic Tract 2. Paleospinothalamic Tract C. Thalamus (VPLc, CL) 3. Corona Radiata D. Cerebral Cortex (S I) Spinothalamic Tract Anteromedial System DRG D
  30. 31. Fast Pain Slow Pain Sharp, pricking Dull, burning Group III (A  ) fiber Group IV (C) fiber Short latency Slower onset Well localized Diffuse Short duration Long duration Less emotional Emotional, autonomic response Not blocked by morphine Blocked by morphine Neospinothalamic Tract Paleospinothalamic Tract Comparison of Fast and Slow Pain ------ Spinothalamic Tract
  31. 32. Fast and Slow Pain
  32. 33. Comparison of Fast and Slow Pain Neospinothalamic Tract Paleospinothalamic tract - spinoreticular tract - spinoreticulothalamic tract
  33. 34. 1. Ascending control “ Gate control theory” of Wall and Melzak (1965) Substantia gelatinosa Rolandi 2. Descending Control “ Stimulation produced analgesia (SPA)” Raphe Magnus ------------ Raphespinal tract (Serotonin) Periaqueductal Gray ----- fibers to raphe magnus Lateral Tegmental Nucleus (Epinephrine) Substantia gelatinosa Rolandi enkephalin cf. endorphine, morphine Control of Pain Transmission
  34. 35. Spinal and Brain Stem Control of Pain
  35. 36. Analgesia - Morphine and Enkephalin opium
  36. 37. Modality: General Sensation from face Receptor: Most receptors in the face 1st Neuron: Trigeminal (Semilunar) Ganglia 2nd Neuron: Trigeminal Sensory Nucleus pain & temperature ---- pars caudalis of spinal tract nucleus of V Ventral and Dorsal Trigeminothalamic Tract 3rd Neuron: Thalamus (VPM) Internal Capsule ----- Corona Radiata Termination: Primary Somesthetic Area (S I) Trigeminothalamic Tract
  37. 38. Trigeminothalamic Tract A. trigeminal ganglion B. trigeminal sensory nucleus C. thalamus (VPM) D. cerebral cortex (S I) 1. spinal tract of trigeminal nerve 2. ventral trigeminothalamic tract 3. dorsal trigeminothalamic tract 4. corona radiata V. trigeminal nerve
  38. 40. Thalamus Ventral Posteromedial (VPM) Nucleus
  39. 41. Spinothalamic Tract & Spinoreticular Tract Widespread cortical region CL (intralaminar thalamic nuclei) reticulothalamic pathways spinoreticular tract Primary Motor Area (M I) VPLc (ventrobasal nuclear complex) (spinal lemniscus) spinothalamic tract thalamus reticular formation NeoSTT PaleoSTT
  40. 42. Spinocerebellar Tract Modality: Unconscious Proprioception Receptor: Muscle spindle, Golgi tendon organ 1st Neuron: Dorsal Root Ganglion Posterior Root , [Posterior Column] 2nd Neuron: 1. Clarke’s column Posterior Spinocerebellar Tract 2. Accessory Cuneate Nucleus Cuneocerebellar Tract 3. Posterior Horn Anterior Spinocerebellar r Tract Termination: Cerebellar Cortex Spinal Cord Ascending Tracts
  41. 43. Spinocerebellar Tract
  42. 44. Spinocerebellar Tract Posterior SCbllT Inferior cerebellar peduncle Post. SCbllT and cuneocerebellar tract posterior white column posterior root Anterior SCbllT superior cerebellar peduncle anterior spinocerebellar tract anterior white commissure posterior root
  43. 45. Predominant Sensory Syndromes <ul><li>Herpes Zoster </li></ul><ul><li>- inflammatory reactions of dorsal root ganglion </li></ul><ul><li>- severe pain on the dermatomes of affected ganglion </li></ul><ul><li>followed by rashes and vesicle </li></ul><ul><li>Tabes Dorsalis </li></ul><ul><li>- common variety of neurosyphilis </li></ul><ul><li>- posterior colum and spinal posterior root lesion </li></ul><ul><li>- loss of discriminative touch sensation and conscious </li></ul><ul><li>proprioception below the level of lesion </li></ul><ul><li>- posterior column ataxia </li></ul><ul><li>- lancinating pain </li></ul><ul><li>- loss of deep tendon reflex (DTR) </li></ul>
  44. 46. Herpes Zoster (Shingles) <ul><li>varicella-zoster virus </li></ul><ul><li>reactivation from </li></ul><ul><li>the dorsal root ganglia </li></ul><ul><li>unilateral vesicular </li></ul><ul><li>eruption within </li></ul><ul><li>a dermatome </li></ul><ul><li>T3 to L3 dermatome </li></ul><ul><li>lesions are frequent </li></ul><ul><li>zoster ophtahalmicus </li></ul><ul><li>(ophthalmic division </li></ul><ul><li>of trigeminal n., V 1 ) </li></ul><ul><li>Ramsey-Hunt syndrome </li></ul><ul><li>(sensory br. of VII) </li></ul><ul><li>acyclovir, antiviral agent </li></ul>
  45. 47. Herpes Zoster (Shingles) Zoster ophthalmicus
  46. 48. Tabes Dorsalis (Neurosyphilis) posterior column lesion - sensory symptoms, posterior column ataxia
  47. 49. Tabes Dorsalis Subacute Combined Degeneration Ataxic Gait and Position: - Watches the ground in walking - Positive Romberg Test - Stick and Stamp Sign Posterior Column Ataxia
  48. 50. Friedreich’s Ataxia posterior spinocerebellar tract lesion - cerebellar ataxia
  49. 51. Muscle Status - Balance and Posture alcohol and cerebellar dysfunction
  50. 52. Syringomyelia initial symptom - bilateral loss of pain and temperature sensation
  51. 53. Syringomyelia initial symptom - bilateral loss of pain and temperature sensation
  52. 54. Trigeminal Neuralgia (tic douloureux) - excruciating episodic pain in the area supplied by trigeminal nerve, especially second and third division - trigger point - intense pain makes the patient grimace (tic) - antiepileptic drug (phenytoin, carbamazepine ) is effective - surgical treatment
  53. 55. Special Sensation Gustatory Sensation (Taste, SVA) ----- Taste Pathway Auditory Sensation (Hearing, SSA) ----- Auditory Pathway Vestibular Sensation (Equilibrium, SSA) ----- Vestibular Pathway Vision (SSA) ----- Visual Pathway Olfaction (Smell, SVA) ----- Olfactory Pathway Sensory System Special Sensation
  54. 56. Taste (Gustatory) Pathway
  55. 57. Modality: Taste Sensation Receptor: Taste Bud Cranial Nerve: VII, IX, X 1st Neuron: Geniculate Ganglion (VII) Inferior Ganglion (IX, X) 2nd Neuron: Nucleus Tractus Solitarius (Gustatory Nucleus) solitariothalamic fiber (central tegmental tract) 3rd Neuron: Thalamus (VPMpc) Internal Capsule ----- Corona Radiata Termination: Gustatory Area Brodmann area 43 & parainsular cortex Taste (Gustatory) Pathway
  56. 58. Taste Bud
  57. 59. SVA (Special Visceral Afferent): Cranial Nerve VII, IX, X
  58. 60. Taste Pathways A. nucleus tractus solitarius (gustatory nucleus) B. thalamus (VPMpc) C. Brodmann area 43 D. parainsular cortex E. parabrachial nucleus 1. solitariothalamic fiber (central tegmental tract) 2. corona radiata VII. facial nerve IX. glossopharyngeal nerve X. vagus nerve
  59. 61. Vestibular Pathway Sense of Equilibrium
  60. 62. Modality: Equilibrium Sensation Receptor: Macula & Crista Ampullaris Cranial Nerve: VIIIv 1st Neuron: Vestibular Ganglion 2nd Neuron: Vestibular Nucleus vestibulothalamic fiber (medial lemniscus) 3rd Neuron: Thalamus (VPLo, VPI?) Internal Capsule ----- Corona Radiata Termination: Primary Vestibular Area ----- Primary Somesthetic Area (Brodmann area 3a, 2v ) Vestibular Pathway
  61. 63. Vestibular Mechanism - Otolithic Membrane
  62. 64. Vestibular Hair Cell Vestibular Receptor
  63. 65. Vestibular Pathway A. Vestibular ganglion B. Vestibular nucleus C. Thalamus (VPLo, VPI?) D. Primary Vestibular Area (S I, Brodman area 3a, 2v) 1. Vestibulothalamic fiber (medial lemniscus) 2. Thalamocortical fiber (corona radiata) VIIIc: Vestibular division of VIIIth nerve
  64. 66. Vestibular Termination <ul><li>Thalmocortical </li></ul><ul><li>connection </li></ul><ul><li>(VPLo  S I) </li></ul><ul><li>Deep, Peripheral </li></ul><ul><li>Somesthetic Cortex </li></ul><ul><li>--- 3a, 2 </li></ul><ul><li>(termination of </li></ul><ul><li>deep PWC-ML </li></ul><ul><li>pathway) </li></ul>
  65. 67. Auditory Pathway
  66. 68. Modality: Auditory Sensation (Hearing) Receptor: Organ of Corti of Cochlear Duct Cranial Nerve: VIIIc 1st Neuron: Spiral Ganglion 2nd Neuron: Cochlear Nucleus, Ventral & Dorsal dorsal, intermediate and ventral acoustic striae trapezoid body lateral lemniscus 3rd Neuron: Inferior Colliculus brachium of inferior colliculus 4th Neuron: Medial Geniculate Nucleus (MG) auditory radiation Termination: Primary Auditory Area (A I) Brodmann area 31, 32 Auditory Pathway
  67. 69. Middle Ear - Sound Amplification
  68. 70. Inner Ear - Cochlear Duct
  69. 71. Organ of Corti
  70. 72. Organ of Corti - Inner and Outer Hair Cell
  71. 73. Auditory Pathways A. spiral ganglion B. dorsal and ventral cochlear nucleus C. inferior colliculus D. medial geniculate nucleus E. Primary auditory area F. superior olivary nucleus G. nucleus of lateral lemniscus 1. acoustic striae & trapezoid body 2. lateral lemniscus 3. brachium of inferior colliculus 4. auditory radiation 5. commissure of inferior colliculus VIIIc. cochlear division
  72. 74. Auditory Pathways A. spiral ganglion B. dorsal and ventral cochlear nucleus C. inferior colliculus D. medial geniculate nucleus E. Primary auditory area F. superior olivary nucleus G. nucleus of lateral lemniscus 1. acoustic striae & trapezoid body 2. lateral lemniscus 3. brachium of inferior colliculus 4. auditory radiation 5. commissure of inferior colliculus VIIIc. cochlear division
  73. 75. Visual Pathway
  74. 76. 3 Tunics Tunica Fibrosa : cornea, sclera Tunica Vasculosa : choroid, ciliary body, iris Tunica Nervosa : retina 3 Chambers Anterior Chamber Posterior Chamber Vitreous Body EYEBALL
  75. 77. Modality: Vision Receptor: Photoreceptor Cell of Retina Cranial Nerve: II (Optic nerve) 1st Neuron: Bipolar Cell 2nd Neuron: Ganglion Cell optic nerve optic chiasm optic tract 3rd Neuron: Lateral Geniculate Nucleus optic radiation Termination: Primary Visual Area (V I) Brodmann area 17 Visual Pathway
  76. 78. 1. Pigment Epithelium - retinal detachment 2. Neuronal Layer (1) Photosensitive Cell Layer Rod Cell, Cone Cell (2) Bipolar Cell Layer Bipolar Cell Horizontal Cell Amacrine Cell (3) Ganglion Cell Layer Ganglion Cell Optic Nerve (II) RETINA - Pars Nervosa
  77. 79. 1. Optic nerve 2. optic chiasm 3. optic tract 4. lateral geniculate body 5. optic radiation 6. visual cortex (striate cortex) 7. Meyer’s loop 8. lateral ventricle Visual Pathway
  78. 80. 1. Optic nerve 2. Optic chiasm 3. Optic tract 4. Lateral geniculate body 5. Optic radiation 6. Visual cortex (Striate cortex) Visual Pathway
  79. 81. Clinical Features of Visual Pathway Lesion 1. optic nerve 2. optic chiasm 3. optic tract 4. & 5. optic radiation A. unilateral blindness B. bitemporal hemianopsia C. left homonymous hemianopsia D. left inferior homony- mous quadranopsia E. left superior homony- mous quadranopsia
  80. 82. Olfactory Pathway Sense of Smell
  81. 83. Modality: Olfaction Receptor: Olfactory Cell of Olfactory Epithelium Cranial Nerve: I (Olfactory Nerve) 1st Neuron: Olfactory Bulb --- Mitral & Tufted Cell olfactory tract o lfactory striae lateral & intermediate olfactory striae Termination: Primary Olfactory Area (Rhinencephalon) piriform lobe (prepiriform cortex, entorhinal cortex) corticomedial amygdala anterior perforated substance (olfactory tubercle) Olfactory Pathway
  82. 84. Olfactory Epithelium Olfactory Receptor
  83. 85. Olfactory epithelium Olfactory nerve (CN I)
  84. 86. Olfactory Epithelium and Olfactory Bulb Olfactory epithelium Olfactory Bulb Glomerulus Mitral cell Tufted cell periglomerular cell Olfactory tract
  85. 87. A. olfactory epithelium B. olfactory bulb C. nucleus of diagonal band of Broca D. periamygdaloid cortex E. cirticomedial amygdala F. entorhinal area G. septal nuclei I. olfactory nerve 1. olfactory tract 2. lateral olfactory stria 3. intermediate olfactory stria 4. medial olfactory stria Olfactory System - Olfactory Pathways
  86. 88. Olfactory Pathways I A. olfactory epithelium B. olfdactory bulb C. anterior olfactory nucleus & olfactory tubercle D. periamygdaloid area E. corticomedial amygdala F. entorhinal area I . olfactory nerve 2. lateral olfactory striae 1. olfactory tract 3. intermediate olfactory striae
  87. 89. A. olfactory epithelium B. olfactory bulb C. nucleus of diagonal band of Broca D. periamygdaloid cortex E. cirticomedial amygdala F. entorhinal area G. mediodorsal thalamic nucleus (MD) I. olfactory nerve 1. olfactory tract 2. lateral olfactory stria 3. intermediate olfactory stria 4. thalamocortical radiation Olfactory System - Connections of Primary Olfactory Cortex

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