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Hearing. Anatomy and Physiology of the ears.

Hearing. Anatomy and Physiology of the ears.



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  • Triggers presynaptic vesicular vesicle to release the neurotransmitter onto the post synaptic sites at the distal ends of spiral ganglion. This lead to activation of the of afferent nerve.

Hearing Presentation Transcript

  • 1. Gerard RecioKamille SalemZaira RiveraMica Pusing3OTB
  • 2.  To distinguish between the two types of deafness To know the proper method of performing the Rinne and Weber tests
  • 3. In doing the experiment there are two tests that we shouldperform. First is the Rinne test. From our group we chose therepresentative to whom we would perform the experiment.One ear of the subject was plugged. On the heel of the hand, atuning fork was set in motion by striking it. At the level of theupper portion of the unplugged ear canal, the stem of thetuning fork was placed on the mastoid processes. When thesound from the vibrating fork disappears, the subject wasasked to make a signal. Then, place the line of the fork in frontof the unplugged ear at a distance of 3 to 6 inches. Whetherthe subject hears any sound or not indicate it. The procedurewas repeated on the other ear.
  • 4. For the next test which is the Weber’s test,another member of the group was selected tobe the subject. On the heel of the hand, thetuning fork was strike. On the forehead of thesubject the stem of the tuning fork wasplaced. We asked the subject to compare thesounds that was heard in each ear. Weindicate whether the sound was heardequally or not.
  • 5.  Outer ear – pinna, external auditory canal Middle ear – tympanic membrane, three ossicles and the Eustachian tube Inner ear – cochlea, semicircular canals, nerves * All three parts are involved in hearing while for vestibular functions, the inner ear is the only one involved.
  • 6. 1. Pinna/auricle/earlobe – funnels the sound waves into the ear2. External auditory canal – passageway of sound to the middle ear; lined with hair3. Eardrum/tympanic membrane – transmits sound from the outer ear to the ossicles4. Malleus, incus, stapes – three small bones of the ear5. Eustachian tube – equalizes the pressure in the middle ear and the throat
  • 7. 6. Cochlea – organ of hearing; Lt. for “snail shell”; has Organ of Corti ▪ Scala tympani ▪ Scala vestibuli ▪ Scala media7. Semicircular canals – three (anterior, lateral, posterior); for balance8. Vestibule – central part of the bony labyrinth
  • 8. Malleus  faceplate of stapes (3/4 of theamplitude of movement)Surface area of tympanic mem. : 55 sq. mm.Surface area of stapes: 3.2 sq. mm.22 TIMES MORE PRESSURE ON THE FLUID.
  • 9.  Reduces the intensity of the sound by as much as 30-40 decibels Latent period of 40-80 ms Stapedius – pulls stapes outward Tensor tympani muscles – pulls malleus inward Reduce ossicular conduction Protect cochlea, mask low-frequency sounds in the env., and dec. sensitivity to own voice
  • 10. Sound energy  Mechanical energy  Hydraulic movements  Chemical energy  Electrical energy  BRAINMechanical Energy: Vibrations of the eardrum  lever-like action of the ossiclesHydraulic Energy: Faceplate and oval window  Organ of Corti
  • 11.  Scala tympani – perilymph  Scala vestibuli – perilymph  Scala media – endolymph Reissner’s membrane (vestibular membrane) – s. vestibuli from s. media Basilar membrane – s. media from s. tympani; modiolus (high freq. at oval window, low freq. near the apex) Organ of Corti – contains a series of electromechanichally sensitive cells, hair cells; transduces pressure waves to action potentials
  • 12. Tympanic membrane>malleus>incus>s tapes>oval window>scala vestibuli>scala tympani>basilar membrane>hair cells receptorsImpedance matching-ossicular system reduce distance but increase the force of movement by 1.3X about 22X pressure exerted in the fluid.
  • 13.  The movement of the basilar membrane cause the hair cell stereocilia to bend. Stereocilia is directionally sensitive: Upward towards scala vestibuli: hair cells depolarized Down towards the scala tympani:hair cell hyperpolarized
  • 14.  From the bending of the stereocilia opens ionic channel>influx of K. Membrane potential decreased to -50mV from 60mV(resting membrane potential) Opens the Ca2+ channel
  • 15. Spiral ganglion (cochlear nerve)> dorsal and ventral cochlear nerve (acoustic striae)>superior olivary nucleus> lateral lemniscus>nucleus of lateral lemniscus>inferior colliculus>medial geniculate nucleus>auditory radiation>heschl gyrus brodmann 41,42
  • 16.  1st order neuron: located in SPIRAL GANGLION 2nd order neuron: dorsal and ventral cochlear nuclei[form 3 groups of acoustic striae(lateral lemniscus): ventral striae-most prominent forms trapeziod body] 3rd order: superior olives nucleus 4th order neuron: medial geniculate nucleus
  • 17.  Area 41 and 42>>Primary auditory area-anterior part: low frequencyPosterior part:reception of high frequency Area 22>>Secondary auditory areaInterpretation of sound and for association of auditory inputs.
  • 18.  Superior olivary nucleus- fibers joins ipsi and contralateral lateral lemnisci. Localization of sound in space Nucleus of lateral lamniscus- send axons on both epsi and contralateral lemnisci. Aids in bilateralism by sending axon to the contralateral side.
  • 19.  Whispered Voice Test Ticking Watch Test Weber Test Rinne Test Schwabach Test
  • 20.  Conductive hearing loss  Neural hearing loss (Nerve deafness)  Mixed hearing loss 
  • 21.  sound vibrations dont go from the air around  a person to the moving bones of the inner ear  sounds are heard, but they are weak,  muffled, and distorted
  • 22.  auditory nerve, which goes from the inner ear  to the brain, fails to carry the sound  information to the brain cause a loss of loudness or a loss of clarity in  sounds. Mixed hearing loss  combination of conductive and neural  hearing losses
  • 23.  Heredity  Diseases of the Ear Injuries of the Ear
  • 24.  born deaf cause is unknown something that happened to the mother  during her pregnancy
  • 25.  Ear infections  cause fluid or mucus to build up inside the ear fluids drain out of the ear or are absorbed into the  body Otosclerosis  common cause of hearing loss hereditary disease in which portions of the middle  ear or inner ear develop growths like bony  sponges can be in the middle ear, the inner ear, or both  places
  • 26.  Meningitis inflammation of the membrane(called the  meninges) that surrounds the brain and the spinal  column
  • 27.  Punctures of the Eardrum a hole in the eardrum, which could be caused by  either injury or disease Nerve Damage result of nerve damage is that the electrical  signals of sounds do not get transmitted from the  ear to the brain
  • 28.  Loud Noises common cause of deafness is repeated or long- term exposure to loud noises often cause moderate to severe hearing loss.
  • 29.  sound-amplifying devices  to aid people who have a hearing  impairment.
  • 30.  Microphone  Amplifier Receiver/ Speaker Battery
  • 31.  picks up sound from the environment converts it into an electrical signal, which it  sends to the amplifier. AMPLIFIER increases the volume of the sound  and sends it to the receiver
  • 32.  changes the electrical signal back into sound  and sends it into the ear those impulses are sent to the brain. BATTERY  provides power to the hearing aid
  • 33.  design technology used to achieve amplification  (i.e., analog vs. digital) special features
  • 34.  Directional microphone T-coil (Telephone switch)  Direct audio input  Feedback suppression 
  • 35.  help you converse in noisy environments allows sound coming from a specific direction  to be amplified to a greater level sound coming from in front of you is  amplified to a greater level than sound from  behind you
  • 36.  allows you to switch from the normal microphone setting to a "T-coil" setting to hear better on the telephone. Direct audio input  allows you to plug in a remote  microphone or an FM assistive  listening system or connect to other  devices
  • 37.  helps suppress squeals when a hearing aid gets too close to the phone or has a loose- fitting earmold
  • 38.  Behind-the-ear (BTE) aids "Mini" BTE (or "on-the-ear") aids In-the-ear (ITE) aids In-the-canal (ITC) aids and completely-in- the-canal (CIC) aids
  • 39.  contained in a small plastic case that rests behind the ear case is connected to an earmold or an earpiece by a piece of clear tubing often chosen for young children because it can accommodate various earmold types can help with all types of hearing loss, from mild to profound Sound travels from the earmold into the ear
  • 40.  fits behind/on the ear, but is smaller very thin, almost invisible tube is used to connect the aid to the ear canal allow not only reduced occlusion or "plugged up" sensations in the ear canal mild hearing loss who can still hear low- and mid-frequency sounds
  • 41.  contained in a shell that fills in the outer part of the ear mild to severe hearing loss it can accommodate directional microphones and other added features
  • 42.  contained in tiny cases that fit partly or completely into the ear canal smallest hearing aids available In-the-canal (ITC) aids works only for mild to moderate hearing loss users sometimes experience feedback noise with this type of hearing aid because the microphone and receiver sit close together
  • 43.  Completely-in-the-canal (CIC) appropriate for mild to moderate hearing loss, and its even smaller than the ITC hearing aid barely visible
  • 44.  Analog hearing aids Digital hearing aids
  • 45.  aids amplify sounds amplify all sounds equally Digital hearing aids contain a computer chip analyzes the sound based on the  persons hearing loss and listening  situation adjusts for feedback
  • 46.  Young, P.A., Young,P.H.,&Tolbert,D. (2008). Basic clinical neuroscience. (2 nd ed.). USA:Lippincott Wlliams and Wilkins Hall, J.E., (2010). Guyton and Hall Textbook of Medical Physiology. (12th ed.). Ganong,William F.(2006).Review of Medical Physiology 23rd edition.San Francisco,California:Lange Medical Publications
  • 47.  http://health.howstuffworks.com/medicine/ modern-technology/hearing-aid3.htm http://science.jrank.org/pages/3242/Hearing. html http://www.fda.gov/MedicalDevices/Products andMedicalProcedures/HomeHealthandCons umer/ConsumerProducts/HearingAids/ucm18 1470.html