Lecture 5 Flashcards by Andrew Glover

Ear - Structures?

-Outer Ear
-Middle Ear
-Inner Ear

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(Ear - Structures)
Outer Ear?

(receives incoming sound waves)
-Auricle (pinna) –> External Auditory Meatus –> Tympanic membrane (eardrum)
-Lined with stratified squamous epithelium + elastic cartilage
-Ceruminous glands produce ear wax

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(Ear - Structures)
Middle Ear?

(transmits sounds from outer to inner ear)
-Housed in tympanic cavity
-Lined with simple squamous epithelium (derived from endoderm)
-Auditory (eustachian) tube = ciliated pseudostratified columnar epithelium (connects middle ear to nasopharynx) (helps to change pressure in order to maintain equilibrium)
-Ossicles: malleus –> incus –> stapes –> oval window
-Round window important for rebounding of sound

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(Ear - Structures)
(Middle Ear)
Auditory (eustachian) tube?

Ciliated pseudostratified columnar epithelium (connects middle ear to nasopharynx) (helps to change pressure in order to maintain equilibrium)

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(Ear - Structures)
(Middle Ear)
Ossicles?

Malleus –> incus –> stapes –> oval window

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(Ear - Structures)
(Middle Ear)
Oval Window important for?

Rebounding of sound

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(Ear - Structures)
(Inner Ear)?

(hearing + balance)
-Bony labyrinth (filled with perilymph) (contains vestibule + semicircular canals + cochlea)
-Membranous labyrinth (filled with endolymph) (contains saccule + utricle + semicircular ducts + cochlear ducts)

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(Ear - Structures)
(Inner Ear)
Bony Labyrinth?

Filled with perilymph
(contains vestibule + semicircular canals + cochlea)

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(Ear - Structures)
(Inner Ear)
Membranous Labyrinth?

Filled with endolymph (contains saccule + utricle + semicircular ducts + cochlear ducts)

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Bony Labyrinth carved out of?

Temporal Bone and contains perilymph (fluid)

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Bony Labyrinth surrounds?

-Cochlea
-Vestibule (middle portion between cochlea + semicircular canals)
-3 semicircular canals

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Membranous Labyrinth lines?

Inside of bony labyrinth and contains endolymph (fluid)

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Membranous Labyrinth surrounds?

-Cochlear duct (inside cochlea)
-Saccule + Utricle (inside vestibule)
-Semicircular ducts (inside semicircular canals)

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(Membranous Labyrinth surrounds)
Cochlear duct?

(inside cochlea)
-Contains scala media (which houses organ of corti)
-Function is hearing

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(Membranous Labyrinth surrounds)
Saccule + Utricle?

(inside vestibule)
-Contains maculae
-Function is motion sense (linear acceleration)

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(Membranous Labyrinth surrounds)
Semicircular ducts?

(inside semicircular canals)
-Contains crista ampullaris
-Function is balance (angular motion)

(Inner Ear - Cochlea)
Cochlea is responsible for?

Hearing
(covered by bony labyrinth)
(contains cochlear duct (covered by membranous labyrinth)

(Inner Ear - Cochlea)
Cochlea consists of 3 chambers?

-Scala vestibuli
-Scala media
-Scala tympani

(Inner Ear - Cochlea)
Cochlea duct?

Scala media (with endolymph)

(Inner Ear - Cochlea)
Cochlea duct contains?

-Organ of corti
-Hair cells with stereocilia
-Tectorial membrane
-Basilar membrane

(Inner Ear - Cochlea)
(Cochlea duct)
Organ of corti?

Receptor organ for hearing

(Inner Ear - Cochlea)
(Cochlea duct)
Hair cells with stereo cilia?

Convert sound to neural impulse

(Inner Ear - Cochlea)
(Cochlea duct)
Tectorial membrane?

Attached to hair cells

(Inner Ear - Cochlea)
(Cochlea duct)
Basilar membrane?

Supports organ of corti
(generates different sound frequencies (base (narrow portion) of basilar membrane (high pitch)) (apex (wide portion) of basilar membrane (low pitch))

(Inner Ear - Cochlea) Displacement of stereo cilia in the hair cells of tectorial membrane results in?

Generation of APs (ex. neural impulse)

(Inner Ear - Sound Transmission) Steps involved in transmission of sound waves?

1) Sound travels up scala vestibuli --> makes waves in perilymph --> transferred to scala media (endolymph) 2) Waves in endolymph move basilar membrane --> stimulates hair cells --> stereo cilia move against tectorial membrane 3) Sound is turned into APs --> neural impulses

(Inner Ear - Sound Transmission) Excess vibrations travel down?

Scala tympani --> absorbed by round window

(Inner Ear - Crista Ampullaris) Location?

Located in semicircular duct (membranous labyrinth)

(Inner Ear - Crista Ampullaris) Function?

Angular motion (acceleration)

(Inner Ear - Crista Ampullaris) Covered by?

Cupula (gelatinous membrane) (movement of endolymph in duct displaces cupola --> stimulates hair cells)

(Inner Ear - Maculae) Location?

Saccule + Utricle of Vestibule

(Inner Ear - Maculae) Function?

Gravity + Linear Acceleration

(Inner Ear - Maculae) Covered by?

Otoconia (little crystals --> push down on stereo cilia of hair cells) (otolithic membrane underlies otoconia)

(Inner Ear - Maculae) Kinocilium?

Microtubules --> interact with stereocilia displaced by otoconia (movement towards kinocilium opens channels; movement away closes channels)