1. Anatomy
   1. External Ear
      1. pinna
      2. helix
      3. anti helix
      4. tragus
      5. antitragus
      6. concha
      7. lobule
      8. external auditory meatus
         1. specialised hair cells secrete ear wax or cerumen
   2. Middle Ear
      1. tympanic membrane
         1. umbo
            1. most depressed part of the tympanic membrane.
         2. pars flaccida
         3. lateral process
         4. pars tensa
      2. ossicles
         1. malleus
         2. incus
         3. stapes
      3. muscles
         1. stapedius
            1. assc. hyperacousia
         2. tensor tympani
      4. oval window
      5. circular window
      6. pharyngotympanic tube
         1. aka eustacian tube
         2. particularly under developed in children (glue ear common)
   3. Inner Ear
      1. Labrynth
         1. vestibular system
            1. semi circular tubes
            2. anterior
            3. posterior
            4. lateral
            5. otolithic organs
            6. Saccule
            7. macula
            8. hair cells
            9. hair bundles (70 x stereo cilia)
            10. 1 x kinocilium
            11. otoconia (calcium carbonate crystals)
            12. Utricle
            13. ampulla(s)
            14. cupula
            15. ampullary nerve
         2. Cochlea
            1. scala vestibuli
            2. vestibular membrane
            3. cochleal duct (scala media)
            4. scala tympani
            5. organ of coti
            6. basilar membrane
            7. tonotopically tuned
            8. High Hz - short and stuff at the round window
            9. Low Hz - widening towards the apex of the cochlea
            10. hair cells
            11. inner hair cells
            12. stereocillia
            13. actually microvilli
            14. ascending height of hairs from inner->outer direction
            15. tip links between hairs
            16. mechanically gated ion channels
            17. opened by bending of adjacent taller hairs
            18. K+ rich endolymph cause K+ to flow into cell and polarise = action potential
            19. outer hair cells
            20. tectorial membrane
         3. vestibulocochlear (VIII) Nerve
   4. bony landmarks
      1. temporal bone
         1. mastoid process
         2. Petrous portion of the temporal bone
         3. tympanic part
   5. Innervation
      1. auricular nerve
         1. Foreign body in the external AM can elicit cough, nausea or even heart rate changes
2. Hearing aids
   1. analog
      1. amplifies all frequencies
   2. digital
      1. tuned to speech or to amplify the frequencies that patient cannot hear
      2. tends to be a shortage on the NHS (lack of trained audiologists to fine tune)
   3. cochlea implant
      1. microphone and sound microprocesser external
      2. implant direct into the cochlea and stimulates the nerves of the basilar membrane
      3. Needs conductive nerves but works int he absence of haircells
      4. can sound 'robotc' since the granularity of the nerves stimulates is wider than natural
3. physiology
   1. otoacoustic emissions
      1. spontaneous otoacoustic emissions (SOAEs)
      2. evoked otoacoustic emissions (EOAEs)
      3. see also clinical diagnosis->surgical interventions
4. Conditions
   1. acoustic neuroma(Vestibular Schwannoma)
      1. tinnitus
      2. very slow onset
      3. lateralised hearing loss 95th cranial nerve close to 6th)
   2. Hearing loss
      1. Conductive
         1. cholesteroma
            1. impaired epithelial cell migration
         2. perforated ear drum
            1. 1 month to heal a simple tear
            2. Myringoplasty for complex tears
            3. facia from temporal bone grafted onto tympanic membrane
         3. glue ear
            1. mid ear infection and inability to drain through pharyngotympanic tube
      2. sensoneuronal
         1. presbyacusis
            1. age related hearing loss
            2. Higher Hz->lower Hz drop off with age
            3. audiometry shows clear sloping from lower Hz to higher Hz
         2. Noise Induced Hearing Loss (NIHL)
            1. audiometry shows ~4KHz dip and may recover a little at 8Khz
            2. Important dB(A) values
            3. cannot hear what someone is saying at 2meters = ~80dB
            4. cannot hear what someone is saying at 1meter = ~90dB
            5. hearing protection must be offered by employers at 85db (for those who want it)
         3. Meniere's disease
            1. intermittent hearing loss
            2. intermittent tinnitus/vertigo
            3. believed to be labrynth fluid related
            4. too much fluid in the cochlea = swelling and/or...
            5. leakage from endolyph and perilymph
            6. treatements
            7. intratympanic gentamycin injection of
            8. analogy with flickering light bulb - brain can deal with no signal/good signal but spurious stimulation causes big issues
            9. risk of hearing loss is 25% due to ototoxicity of -mycin
      3. can be both
         1. barotrauma
            1. rupture of oval window can cause fluid to leak into middle ear
   3. tinnitus
      1. subjective
         1. Meniere's disease
         2. otosclerosis
         3. ear infections
         4. wax
         5. middle ear infection
         6. acoustic neuroma
         7. ototoxic medication
         8. head injury/whiplash
         9. temporomandibular joint
      2. objective
         1. the sound of blood flowing in narrowed arteries in the neck (also can be subjective)
         2. "murmur" defective heart valve.
   4. otitis externa
      1. 'swimmer's ears'
         1. bacteria/irritating fluid strips the natrual protection of the ear
         2. use custom earplugs to keep your ears dry
      2. cotton buds
         1. nothing smaller than your elbow should go in your ear
   5. microtia
      1. congenital deformity of the pinna
      2. occurs in 1 out of about 8,000-10,000 birth
      3. cosmetic surgery
5. ototoxicity
   1. aminoglycosides
      1. vancomycin
         1. almost anything ending in -mycin
      2. ototoxic for fetus as well as adult
   2. salicylates
   3. quinines
   4. ibuprofen
6. Clinical diagnosis
   1. aims
      1. determine unilateral/bilateral
      2. conductive or sensoneuronal loss
      3. occulusion
      4. infection
   2. tuning fork screening
      1. Rinne's test
         1. +ive : AC>BC
            1. indicates normal hearing or sensoneuronal loss
         2. -ive: BC>AC
            1. indicates conductive hearing loss
            2. False -ive occurs where NIHL sensoneuronal loss is profound and adjacent cochlea picks up BC
      2. Webber test
         1. Normal or bilateral SNHL : no lateralisation
         2. patient with a unilateral SNHL hears the sound louder in the unaffected ear
         3. patient with unilateral CHL hear the tuning fork loudest in the affected ear
   3. Test used in practice
      1. PTA (Pure tone audiometry)
      2. tympanometry
   4. surgical interventions
      1. insertion of gromit for glue ear
      2. insertion of cochlae implant for profound SNHL
         1. see also Hearing Aids
      3. cosmetic ear reconstruction for microtia
   5. otoacoustic emissions
      1. can use sensitive mic to detect sounds in new born (no sounds = deaf)