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Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
Physiology of hearing 21st july 11
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Physiology of hearing 21st july 11

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  • 1. PHYSIOLOGICAL BASIS OF HEARING
  • 2.  
  • 3.  
  • 4.  
  • 5. FUNCTION OF EXTERNAL EAR
  • 6.  
  • 7. FUNCTION OF MIDDLE EAR
  • 8. FUNCTIONS OF MIDDLE EAR: 1. IMPEDANCE MATCHING
  • 9. <ul><li>1.Diameter of TM is 17 times </li></ul><ul><li>2.ossicolar lever action increases the pressure 1.3 times </li></ul><ul><li>Total increase will be 22 times </li></ul>
  • 10. 2.ATTENUATION REFLEX
  • 11. STRUCTURE OF INNER EAR
  • 12.  
  • 13. FUNCTION OF INNER EAR <ul><li>The inner ear has 2 main functions: </li></ul><ul><li>Mechanical frequency analysis: </li></ul><ul><li>2. Sensory transduction: </li></ul><ul><li>Generated pressure waves which </li></ul><ul><li>are transformed into neural impulse. </li></ul>
  • 14. BASEMENT MEMBRANE 1. FREQUENCY ANALYSIS
  • 15. PLACE PRINCIPLE
  • 16. 2.SENSORY TRANSDUCTION IN INNER EAR Reticular lamina Rod of corti Pillar cell
  • 17. SENSORY TRANSDUCTION IN INNER EAR <ul><li>Kinocilia / Stereocilia are Linked </li></ul><ul><li>Displacement Opens K + Channels </li></ul><ul><li>Depolarization -> release of glutamate </li></ul><ul><li>K + flows through cell </li></ul><ul><li>Glutamate -> increase spike rate in auditory nerve </li></ul>
  • 18. ENDOCOCHLEAR POTENTIAL
  • 19.  
  • 20. <ul><li>Lesions of inner ear or </li></ul><ul><li>cochlear nuclei ,pons will </li></ul><ul><li>produce total N deafness </li></ul><ul><li>Lesions central ,cochlear </li></ul><ul><li>Nuclei primarily affect the </li></ul><ul><li>ability to localize sound </li></ul><ul><li>direction </li></ul>Primary Auditory area 41,42 Tranverse temporal gyri of Heschl
  • 21. Pathophysiology of hearing <ul><li>Conduction deafness </li></ul><ul><li>Sensorineural deafness </li></ul>
  • 22. <ul><li>Common tests differentiating b/w nerve & bone conduction </li></ul><ul><li>1.Rinnes </li></ul><ul><li>2.Webers </li></ul><ul><li>3.Audiometer </li></ul>
  • 23. Rinnes compares AC-BC <ul><li>Normal : AC >BC Rinnes + ve </li></ul><ul><li>Conductive deafness: BC > AC Rinnes – ve </li></ul><ul><li>Sensorinueral deafness: Reduced rinnes +ve </li></ul><ul><li>AC >BC </li></ul>
  • 24. Webers compares bone conduction of 2 ears, <ul><li>Normal : centralized </li></ul><ul><li>Conductive deafness: lateralized to diseased </li></ul><ul><li>Sensorinueral deafness:lateralized to normal </li></ul>
  • 25. THANK YOU
  • 26.  
  • 27. TONOTOPICAL MAPPING
  • 28. br of inf col 41,42
  • 29.  
  • 30. Loss of high frequency tones in old age
  • 31. stapedius TT
  • 32.  
  • 33.  

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