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The Outer Ear

The Outer Ear. SPA 4302 Summer 2004. External Auditory Canal. lateral portion-cartilage medial portion-osseous lined with epidermal (skin) tissue hairs grow in lateral part cerumen (ear wax) secreted in lateral part. Usually curved. Outer Ear Functions 1. Amplification / Filtering

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The Outer Ear

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  1. The Outer Ear SPA 4302 Summer 2004

  2. External Auditory Canal • lateral portion-cartilage • medial portion-osseous • lined with epidermal (skin) tissue • hairs grow in lateral part • cerumen (ear wax) secreted in lateral part. • Usually curved.

  3. Outer Ear Functions 1 • Amplification / Filtering -- increases sounds between 1500 and 7000 Hz by 10 to 15 dB -- produced by resonance of Concha -- 5000 Hz E.A.Canal -- 2500 Hz

  4. Outer Ear Functions 2 • Protection -- medial displacement of ear drum -- curvature of canal -- hairs -- cerumen -- skin migration

  5. Outer Ear Functions 3 • Localization -- The ability to identify the location of a sound source

  6. Otoscopy • Viewing outer ear and TM Looking for: • Landmarks, • Evidence of infection • Other Anomalies

  7. Lateral Process (Malleus) = Annulus Malleus Manubrium Umbo Cone of Light

  8. Epidermal migration produces “wrinkles”

  9. Disorders: • Blockage: with earwax, foreign bodies, pus. • Otitis Externa: swimmer's ear. • Fungal or Bacterial in origin. • More frequent in ears with small canal • openings that cannot dry out as easily. • This is also sometimes a problem for people wearing hearing aids.

  10. Otitis Externa

  11. Cerumen

  12. A Cerumen Tunnel

  13. Car Accident Victim Who just didn’t “feel right” afterward…

  14. Another Foreign Object

  15. Exostoses: Benign bony growths in the outer ear canal • Contrast with Osteomas

  16. A False Tympanic Membrane • A layer of dead skin cells builds up in persons who use earplugs or some hearing aids frequently

  17. Injuries to Ear Canal

  18. AQ-tip Victim

  19. Squamous Cell Cancer

  20. Malformations: congenital, traumatic or surgical. • Microtia: external ear is small, malformed • Atresia: ear canal is closed off. • Post-cancer surgery.

  21. Congenital Malformation

  22. Microtia

  23. Anotia: Pre- and Post-Op

  24. Mastoiditis

  25. Hearing Loss accompanying these disorders: • Blockage or atresia: • moderate flat conductive hearing losses. • usually medically or surgically treatable. • additional HL if congenital --associated problems w/ cochlea • Surgical or traumatic: • mid to high frequency conductive. • prosthetics available, expensive.

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