Otitis media

Otitis media is a condition affecting the middle ear. It is caused by inflammation and infection of the middle ear canal. the-human-ear

 Middle ear:

behind tympanic membrane

  • contains 3 auditory ossicles: maleus, incus, stapes

  • maleus articulates with tympanic membrane

  • stapes articulates with the oval window

This condition may result in hearing loss as severe damage occurs and scar tissue accumulates as a result of recurrent severe improperly or untreated infections and inflammation of the middle ear. Individuals may be especially prone to hearing loss or impairment when the infection or inflammation affects the bones of the ear as they are instrumental in conveying sounds waves. 

Hearing:

 

  • sound is generated by waves transduced into energy

  • sound waves into auditory canal

  • tympanic memebrane will be impacted by sound

  • transmits from membrane to maleus

  • waves are converted to mechanical force by bones

  • then transmitted to cochlear

  • sound waves transmitted into fluid filled chamber of cochlea

  • fluid waves move hair cells

 

  1. The outer part of the ear collects sound.

  2.  That sound pressure is amplified through the middle portion of the ear and, in land animals, passed from the medium of air into a liquid medium.

  3. The change from air to liquid occurs because air surrounds the head and is contained in the ear canal and middle ear, but not in the inner ear.

  4. The inner ear is hollow, embedded in the temporal bone, the densest bone of the body.

  5. The hollow channels of the inner ear are filled with liquid, and contain a sensory epithelium that is studded with hair cells.

  6. The microscopic “hairs” of these cells are structural protein filaments that project out into the fluid. mechanical waves deform the hair cells. sound waves bends hairs

  7. The hair cells are mechanoreceptors that release a chemical neurotransmitter when stimulated.

  8. Sound waves moving through fluid push the filaments; if the filaments bend over enough it causes the hair cells to fire. cell membranes ion channels open

  9. In this way sound waves are transformed into nerve impulses.

Observed symptoms of Otitis media may include the following:otitis-media

  • Severe retraction or perforation of the eardrum (a hole in the eardrum)
  • Scarring or erosion of the small, sound conducting bones of the middle ear
  • Chronic or recurring drainage from the ear
  • Inflammation causing erosion of the bony cover or the facial nerve, balance canals, or cochlea (hearing organ)
  • Erosion of the bony borders of the middle ear or mastoid, resulting in infection spreading to the meninges (the coverings of the brain) or brain
  • Presence of cholesteatoma (a destructive and expanding sac in the middle ear caused by accumulation of dead cells by repeated middle ear infections)
  • Persistence of fluid behind an intact eardrum

Martini, Fredric, H. 2006. Fundamentals of anatomy and physiology. 7th ed. Pearson Education Inc. USA.

Maryland Hearing and Balance Center. 2009.Chronic Otitis Media. retrived March 30, 2009 from http://images.google.ca/imgres?imgurl=http://www.umm.edu/otolaryngology/images/L_cholest.jpg&imgrefurl=http://www.umm.edu/otolaryngology/ear_infections.htm&usg=__Xju8_vmjCabTtFUyoV_lUUrsTlM=&h=366&w=500&sz=38&hl=en&start=10&tbnid=sig3LUsfU-Sc_M:&tbnh=95&tbnw=130&prev=/images%3Fq%3Dotitis%2Bmedia%26gbv%3D2%26hl%3Den%26sa%3DX

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