Ch 10 PNS, Part 4 (Hearing)

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Ch 10 PNS, Part 4 (Hearing)
Lend me your ear.

• Learning Objectives
• Be able to identify the structures of the ear
  (all)
• Discuss the bones of the middle ear
• Explain how we hear
• Explain the mechanisms of balance equilibrium
  in the ear

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CSI Can You Spot the Ear?

• http//video.google.com/videoplay?docid-793311698
  8114927395total36start10num10so0typesear
  chplindex9

More info please gt
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Vacanti Mouse

• It might look like the work of a mad scientist
  but the Vacanti mouse with what appears to be a
  human ear growing on its back is the real deal.
  You won't find this mouse at the circus it was
  created at the University of Massachusetts in
  1997. Dr. Charles Vacanti developed the mouse by
  putting a mold resembling the shape of a human
  ear onto its back.
• Dr. Vacanti is helping researchers fine tune a
  technology that will let them re-grow ears and
  noses for people. It was a plastic surgeon who
  suggested growing ears on mice after seeing kids
  who were born with out ears or who'd had them
  torn off in accidents.
• The 'ear' mold was made from special fibers that
  are biodegradable, much like dissolving stitches
  that doctors often use. Before the mold is
  implanted into the back of a hairless mouse, it
  is covered with cow cartilage cells. Blood from
  the mouse helps the cartilage cells grow and
  eventually replace the fibers. Researchers say
  that the rodent could have the ear removed and
  still remain alive and healthy.

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Practice Activity How Well Do You Know The Parts
of the Ear?

• Answer question 10, Page 211 in your workbook
  now.

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Hearing and Balance Pgs 210-211

• The three parts of the ear are the ______,
  ______, and ________ ear
• The outer and middle ear are involved with
  _______
• The inner ear functions in both hearing and
  ________
• Receptors for hearing and balance
• Respond to separate stimuli
• Are activated independently

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Outer, Middle and Inner Ear
Label or bracket the three regions of the ear
outer, middle and inner on your diagram.
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Outer Ear

• The auricle or ______ is composed of
• The helix (rim)
• The lobule (earlobe)
• External auditory canal
• Short, curved tube filled with ceruminous or ____
  glands
• Tympanic membrane or ________
• Thin connective tissue membrane that vibrates in
  response to sound
• Transfers sound energy to the middle ear ossicles
  
• Boundary between outer and middle ears

pinna
wax
eardrum
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Middle Ear

• A small air-filled mucosa-lined ______
• Flanked laterally by the ________
• Flanked medially by the oval and round windows
• Pharyngotympanic tube connects the middle ear
  to the nasopharynx
• _______ ________ in the middle ear cavity with
  the external air pressure

cavity
eardrum
Equalizes pressure
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Middle Ear
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Bones of the Middle Ear

• The tympanic cavity contains three small bones
  the ______,______, and ______.
• Transmit vibratory motion of the eardrum to the
  oval window

malleus
incus
stapes
These bones are formally named the "malleus", the
"incus", and the "stapes", but they are more
commonly known as the "hammer", the "anvil" and
the "stirrup".
Porpoise inner ear bones
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Inner Ear

• ______ labyrinth
• Tortuous channels worming their way through the
  temporal bone
• Contains the _________, the __________, and the
  _________________
• Filled with fluid called _________
• __________ labyrinth
• Series of membranous sacs within the bony
  labyrinth
• Filled with a potassium-rich fluid

Bony
vestibule
cochlea
semicircular canals
perilymph
Membranous
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Vestibule

• The central egg-shaped cavity of the bony
  labyrinth
• Suspended in its perilymph are two sacs the
  saccule and utricle
• The saccule extends into the cochlea
• The utricle extends into the semicircular canals
• These sacs
• House equilibrium receptors called maculae
• Respond to gravity and changes in the position of
  the head

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Semicircular Canals

• Three canals that each define two-thirds of a
  circle and lie in the three planes of space
• Membranous semicircular ducts line each canal and
  communicate with the utricle
• The ampulla is the swollen end of each canal and
  it houses equilibrium receptors in a region
  called the crista ampullaris
• These receptors respond to angular movements of
  the head

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Cochlea

• A spiral, conical, bony chamber that
• Extends from the anterior vestibule
• Coils around a bony pillar called the modiolus
• Contains the cochlear duct, which ends at the
  cochlear apex
• Contains the organ of Corti (hearing receptor)

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Internal Ear Anatomy

• Instructions Label the malleus, incus,
  stapes, eardrum, cochlea, vestibule, and
  semicircular canals on your practice diagram now.

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How Do We Hear?

• Sound vibrations beat against the eardrum
• The eardrum pushes against the ossicles, which
  presses fluid in the inner ear against the oval
  and round windows
• This movement sets up shearing forces that pull
  on hair cells
• Moving hair cells stimulates the cochlear nerve
  that sends impulses to the brain

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Hearing Balance

• http//video.google.com/videoplay?docid-481194810
  1588376689qbalance2Bmiddleeartotal26start
  0num10so0typesearchplindex0

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Balance Equilibrium

• Vestibular apparatus __________
• in the semicircular canals and vestibule
• Maintains our _________________ in space
• Vestibular receptors monitor static equilibrium
• Semicircular canal receptors monitor dynamic
  equilibrium

equilibrium receptors
orientation and balance
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Balance Equilibrium continued

• Maculae are the sensory receptors for static
  equilibrium
• Contain supporting cells and hair cells
• Otolithic membrane is a jellylike mass studded
  with tiny CaCO3 stones called _________
• Utricular hairs respond to ________movement
• Saccular hairs respond to _______ movement

otoliths
horizontal
vertical