335 15.1 Audition

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  1. ear as an energy transducer 5
    • acoustal - air molecule compression waves
    • mechanical - tissue vibration
    • hydraulic - liquid compression waves
    • mechanical - tissue comprehension
    • electrical - nervous transmission
  2. the outer ear - pinna
    • helix
    • tragus (part used to block ears)
    • riented forward
    • attaches to temporal bone lateral to the petrous prtion
    • made up of cartilage
    • loss of pinna results in -3 to -5 dB of loudness
  3. outer ear - EAM external auditory meatus
    • 2-3 cm long
    • curved, irregular canal
    • made up of cartilage and bone segments
    • from the Tm it angles down for drainage in adults
    • secretes cerumen (wax) and grows hair)
  4. middle ear - tympanic membrane
    • medial boundary of the outer ear
    • lateral boundary of the middle ear
    • sits at a 45 degrees to the EAM floor
    • cone shaped
    • extremely thin, pliable, tough
    • composed of three layers
  5. middle layer of the TM
    • 2 sets of fibers
    • radiating - course in different directions
    • circular - course in different directions
    • fibers are deficient at the notch of Rivinus
    • flaccid section (pars flaccida) (void of fibers)
    • behind it is the manubrium of the malleus (first ossicle)
    • center of the umbo
  6. three layers of the TM
    • outer - continuous with the cutaneous tissue of the EAM
    • inner - continuous with the mucous lining of the middle ear
    • middle
  7. middle ear - ossicles
    • malleus - hammer
    • incus - anvil
    • stapes - stirrup
    • smallest bone in the body
  8. middle ear - osscisle function
    • their articulatory chain transmits the sound energy to the inner ear and in doing so
    • amplifies lox intensity sounds
    • attenuates high intensity sounds somewhat (diminish really loud sounds)
    • protective mechanism
  9. malleus landmarks
    • manubrium (leg) attaches to the umbo and along the length of the manubrium
    • head of the malleus (top heavy part) articulates with the body of the incus (second osscile)
  10. incus landmarks
    • body of the incus articulates with the head of the malleus
    • two processes
    • long proccess articultea with the head of stapes (third ossicle)
    • long process that curves
  11. stapes
    • head of the stapes articulates with the long process of the incus
    • has two crura which connect to an oblong footplate
    • footplate articulates with the vestibule at the oval window - entrance to the inner ear
  12. muscles of the middle ear
    • tensor tympani
    • stapedius
  13. tensor tympani
    • o - temporal bone canal on the anterior wall
    • ins - upper maubrium of the malleus
    • inn - V Trigeinal Nerve
    • f - draws the malleus medially and anteriorly to reduce moevement of the ossicular chain and the tympanic membrane (protects the ossicular chain and ear)
  14. stapedius
    • o - temporal bone canal on the posterior wall
    • ins - head of the stapes
    • inn - VII Facial
    • F - draws the stapes posteriorly to reduce movement of the ossicular chain and reduce compression of the oval window (protects the ossicular chain and ear)
  15. acoustic reflex
    • created by both middle ear muscles working together
    • evoked at 80 - 90 dB threshold
    • even expectation of sound can trigger it
  16. problem with acoustic reflex
    • latent response - ineffective in explosive noises
    • fatigues over time - ineffective in long exposures of sound
  17. middle ear landmarks and topographical anatomy
    six walled irregularly shaped chamber
  18. superior wall
    • roof
    • brain
  19. inferior eall
    • floor
    • jugular vein
  20. lateral
    • membranous
    • external auditory meatus
  21. medial
    • labyrinthian
    • vestibule and cochlea
  22. anterior
    • carotid
    • carotid artery and Eustachian Tube
  23. posteroir
    • mastoid
    • mastoid hair cells
  24. the inner ear 2 parts
    • cochlear - end organ for hearing
    • vestibular - end organ for balance
  25. labyrinths in the cochlea
    • bony
    • membranous
  26. bony labyrinth 3 parts
    • vestibule
    • semicircular canals
    • bony cochlea
  27. vestibule
    • area of COM btw the sensation areas of balance and hearing
    • communicate with the middle ear at the oval window
    • filled with the footplate of the stapes ont he medial wall of the middle ear
  28. bony semicircular canals
    • 3 canals
    • all filled with fluid
    • responsible for balance
    • situated at nearly right angles to each other
    • posterior
    • superior
    • lateral (AKA external or horizontal)
    • slight dilation where each joins at the vestibule is called its ampulla
  29. bony cochlea
    • fluid filled
    • center core - modiolus
    • projecting spiral shelf - spiral lamina
    • completes 2 3/4 spiral turns
    • ends at the apex - helicotrema
  30. bony cochlea openings
    • at the vestibule - sound coming in
    • at the round window (middle ear) - sound going out (sound that does not go to the brain)
  31. Perilymph
    • extra fine filtrate of blood
    • thin, watery in composition
    • originiates from the membrane lining in the bony labyrinth
    • similar to cerebrospinal fluid from the covering of the brain
    • NOT in the area where the cells are - not in middle membrane
  32. membranous cochlea
    • follows the same shape as the bony cochlea
    • formed by two membranes which arise from the spiral lamina and insert in the outer wall of the bony cochlea
  33. two membranes of the cochlea
    • Reissner's membrane - separates top and middle
    • Basilar membrane - inserts at the spiral ligament - separates middle and bottom
  34. membranous cochlea AKA
    • scala media
    • cochlear duct
  35. membranous cochlea - 2 chambers
    • scala vestibuli - communicates with the vestibule
    • scala tympani - communicates eith the tympanic cavity (round window / middle ear)
    • communicate with each other at the helicotrema
  36. scala media
    • cochlear duct
    • upper wall Reissner's membrane
    • lower wall is Basilar membrane
    • tectorial membrane
  37. the basilar membrane supprts the...
    organ of corti which lies within the scala media (has all t=of the cells required for hearing)
  38. the tectorial membrane arises near
    the edge of the spiral lamina and extends over the organ of corti
  39. organ of corti landmarks
    • two pillar (rods) of Corti - inner and outer hair cells
    • tunnel of corti between then is filled with cortilymph
  40. path of sound to the brain
    • acoustic energy - gathered by auricle, channeled in EAM
    • converts to mechanical - strikes and vibrates the tympanic membrane
    • mechanical - malleus, incus, stapes, oval window,
    • converts to hydraulic - vibrates the footplate in the wall of the vestibule
    • hydraulic - (perilymph) vestibule, scala vestibuli
    • converts to mechanical when compresses Reissner's membrane
    • mechanical and hydraulic - (in cochlea) endolymph, compresses tectorial membrane, disturbs hair cells in organ of corti
    • at same time - elcetrical energy - VIII to the brain, temporal lobe, Brodman's area 41, Heschel's gyrus
  41. if energy does not go to the brain...
    • compresses the Basilar's membrane (mechanical)
    • Hydraulic energy - perilymph (scala tympani)
    • round window (secondary tympanic membrane) - middle ear
    • dissipates
Card Set:
335 15.1 Audition
2012-04-25 13:51:38

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