Histology of the Ear

Question 1

the middle ear is on the ____ side of the tympanic membrane

Answer 1

medial

Question 2

How is the middle ear connected to the nasal cavity?

Answer 2

by the auditory/eustachian tube

Question 3

The middle ear contains what three bones?

Answer 3

malleus, incus, and stapes

Question 4

the foot of the stapes sits on the ___ ____

Answer 4

oval window

Question 5

the external and middle ear are filled with what?

Answer 5

air

Question 6

The inner ear is embedded in the bone of the ___ ___ of the ____ bone

Answer 6

The inner ear is embedded in the bone of the petrous pyramidof the temporal bone

Question 7

The inner ear contains the ____ canals, _____, and _____. It also contains Cranial Nerve _____.

Answer 7

The inner ear contains the semicircular canals, vestibule and cochlea. It also contains Cranial Nerve VIII.

Question 8

The internal ear transmits _____ information to the brain via the _____ division of ______ regarding the ____ and _____ of the ____ (equilibrium)

Answer 8

The internal ear transmits proprioceptive information to the brain via the vestibular division of CN VIII regarding the position and movement of the head (equilibrium)

Question 9

The internal ear transmits ____ information to the brain via the _____ division of _____ regarding the sense of _____.

Answer 9

The internal ear transmits auditory information to the brain via the cochlear division of CN VIII regarding the sense of hearing.

Question 10

The two parts of the internal ear are the _____ labyrinth and the ____ labyrinth

Answer 10

The two parts of the internal ear are the bony labyrinth and the membranous labyrinth

Question 11

Bony Labyrinth:

• Series of _____ located within ____ part of ____bone and contain____ fluid (____) in which _____ ______ is suspended
• Parts: _____, ______ canals and ______

Answer 11

Bony Labyrinth:

• Series of cavities located within petrous part of temporal bone and contain clear fluid (perilymph) in which membranous labyrinth is suspended
• Parts: vestibule, semicircular canals and cochlea

Question 12

______closely resembles CSF (rich in ____ and poor in ____)

Answer 12

Perilymph closely resembles CSF (rich in Na+ and poor in K+)

Question 13

The superior, posterior, and lateral loops of the semicircular canals are ______ to each other in order to detect all planes of movement.

Answer 13

The superior, posterior, and lateral loops of the semicircular canals are perpendicular to each other in order to detect all planes of movement.

Question 14

The semicircular canals are connected to the _____.

Answer 14

The semicircular canals are connected to the vestibule.

Question 15

The ____ window opens into the vestibule, while the ___ window leads out of the vestibule.

Answer 15

The oval window opens into the vestibule, while the round window leads out of the vestibule.

Question 16

inside semicircular canals: _____ ______

-contains own opening filled with ______

Answer 16

inside semicircular canals: semicircular ducts

-contains own opening filled with endolymph

Question 17

Membranous Labyrinth:

• Interconnected _____ ____ and ____ located within _____ _____
• Filled with ______and surrounded by _____

Answer 17

Membranous Labyrinth:

• Interconnected membranous sacs and tubes located within bony labyrinth
• Filled with endolymph and surrounded by perilymph

Question 18

_____ resembles intracellular fluid (rich in ___ and poor in ___)

Answer 18

Endolymph resembles intracellular fluid (rich in K+ and poor in Na+)

Question 19

endolymph is made by cells located within ____ _____

good for proper transduction of _____and _____ signals

Answer 19

endolymph is made by cells located within membranous labyrinth

good for proper transduction of hearing and vestibular signals

Question 20

Membranous Labyrinth Parts:

• ____ ____ (scala media) located within bony cochlea; contains _____ for hearing
• Semicircular ducts (located within ______)
• _____ and _____ (located within vestibule)
• Semicircular ducts, utricle and saccule contain _____ ______

Answer 20

Membranous Labyrinth Parts:

• Cochlear duct (scala media) located within bony cochlea; contains receptors for hearing
• Semicircular ducts (located within semicircular canals)
• Utricle and saccule (located within vestibule)
• Semicircular ducts, utricle and saccule contain vestibular receptors

Question 21

the utricle is next to the ____ ____

Answer 21

semicircular ducts

Question 22

The saccule is attached to the ____ and the ___ _____

Answer 22

The saccule is attached to the utricle and the cochlear duct

Question 23

the _____ cell bodies of the cochlear nerve surround the ____ of the _____

Answer 23

the bipolar cell bodies of the cochlear nerve surround the spiral of the cochlea.

Question 24

Three sensory areas of the membranous labyrinth:

1. Macula of ____ and macula of ____. *
2. Three _____ _____ of the semicircular canals. *
3. ____ of ____ of the ____.

Answer 24

Three sensory areas of the membranous labyrinth:

1. Macula of utricle and macula of saccule. *
2. Three crista ampullaris of the semicircular canals. *
3. Organ of Corti of the cochlea.

Question 25

The ______ of the utricle and saccule:

____ and ____ information to the CNS on the____ of the ____ in ____

Answer 25

The maculae of the utricle and saccule:

receive and transmit information to the CNS on the position of the head in space

Question 26

The three ________ _______of the semicircular canals:

receive & transmit information to the CNS on the _____ of ______ of the head.

Answer 26

The three crista ampullaris of the semicircular canals:

receive & transmit information to the CNS on the direction of movement of the head.

Question 27

Two Cell Types of the Cristae and Maculae:

1) ___(receptor) cells - ____cells which have a tuft of ____-____ ______and a single ____-_____ _____(kinocilium) at the ____ (apical) surface.
2) ____ cells - ____ ______cells each containing a ____located _____ and _____located _____.

Answer 27

Two Cell Types of the Cristae and Maculae:

1) Hair (receptor) cells - columnar cells which have a tuft of non-motile stereocilia and a single non-motile cilium (kinocilium) at the free (apical) surface.
2) Supporting cells - tall columnar cells each containing a basally located nucleus and apically located microvilli.

Question 28

Processes from _____ neurons, whose cell bodies are located in the _____ ______, terminate on the ____ surfaces of hair cells.

Answer 28

Processes from bipolar neurons, whose cell bodies are located in the vestibular ganglia, terminate on the basolateral surfaces of hair cells.

Question 29

Two types of hair cells:

a) _____ hair cells: ___-shaped cells, surrounded by a cup-shaped afferent nerve ending called a ____or ____.
b) _____hair cells: ____-shaped cells, ____ afferent and ____ nerve endings.

Answer 29

Two types of hair cells:

a) Type I hair cells: flask-shaped cells, surrounded by a cup-shaped afferent nerve ending called a calyx or chalice.
b) Type II hair cells: rod-shaped cells, smaller afferent and efferent nerve endings.

Question 30

The stereocilia of hair cells are arranged in ____

Answer 30

rows

Question 31

____ links individual stereocilia rows

Answer 31

filament

Question 32

the _____ recess is where the utricle is found.

Answer 32

elliptical

Question 33

the ___ recess is where the saccule is found.

Answer 33

spherical

Question 34

the _____ region of the utricle has no hairs

Answer 34

nonsensory

Question 35

The _____ of the saccule and utricle both consist of a flattened sheet of ______ cells covered by an _____ membrane, a gelatinous _____ layer containing crystals of _____ ______.

Answer 35

The maculae of the saccule and utricle both consist of a flattened sheet of neuroepithelial cells covered by an otolithic membrane, a gelatinous glycoprotein layer containing crystals of calcium carbonate (otolith or otoconia).

Question 36

Cristae Ampullaris:

Located in the _____ ______ are ____-shaped structures which extend into the ____ of the _____ labyrinth.

Answer 36

Cristae Ampullaris:

Located in the semicircular canals are saddle-shaped structures which extend into the lumen of the membranous labyrinth.

Question 37

cristae ampullaris are covered by a layer of gelatinous ______ called a _____

Answer 37

cristae ampullaris are covered by a layer of gelatinous glycoprotein called a cupula (cup-shaped).

Question 38

endolymph drains through the _______ duct

Answer 38

endolymphatic duct

*if this doesn’t drain, it can cause vestibular AND hearing problems!

Question 39

the perilymphatic duct drains into the ______ _____.

Answer 39

subarachnoid space

Question 40

Scala vestibule communicates with the ____ ____ and surrounds the ____ _____.

Answer 40

Scala vestibule communicates with the oval window and surrounds the cochlear duct.

Question 41

The scala tympani leads to the ____ _____.

Answer 41

round window

Question 42

The cochlea consists of central pillar (_____) around which a hollow bony tube makes 2¾ spiral turns, and each successive turn is of a _____radius (____ shape)

Answer 42

The cochlea consists of central pillar (modiolus) around which a hollow bony tube makes 2¾ spiral turns à each successive turn is of a smaller radius (conical shape)

Question 43

Sound waves come through the _____ear and hit the _____ membrane, causing it to vibrate. The ____ will push on the ____window and cause fluid to go to the ____ _____. The fluid then goes back to the _____ ______ and escapes through the _____ window.

Answer 43

Sound waves come through the external ear and hit the tympanic membrane, causing it to vibrate. The stapes will push on the oval window and cause fluid to go to the scala vestibuli. The fluid then goes back to the scala tympani and escapes through the round window.

Question 44

The spiral ganglion contains the cell bodies of what cranial nerve?

Answer 44

CN VIII

Question 45

What are the three fluid filled compartments of the cochlea?

Answer 45

scala media, scala vestibuli, scala tympani

Question 46

The vestibular membrane separates the ____ _____from the ____ _____.

Answer 46

The vestibular membrane separates the scala vestibuli from the scala media.

Question 47

The basilar membrane separates the ____ ____ from the ____ ____.

Answer 47

The basilar membrane separates the scala media from the scala tympani.

Question 48

scala vestibuli and scala tympani contain _____ and are continuous with each other at _____ of cochlea (_____)

Answer 48

scala vestibuli and scala tympani contain perilymph and are continuous with each other at apex of cochlea (helicotrema)

Question 49

cochlear duct is part of ______labyrinth

Answer 49

cochlear duct is part of membranous labyrinth

Question 50

scala vestibuli communicates with ____ at base of cochlea and with ____ _____ at apex of cochlea (helicotrema) –> scala _____ spirals from apex to base of cochlea –> communicates with tympanic cavity via _____window (closed by secondary tympanic membrane)

Answer 50

scala vestibuli communicates with vestibule at base of cochlea and with scala tympani at apex of cochlea (helicotrema) –> scala tympani spirals from apex to base of cochlea –> communicates with tympanic cavity via round window (closed by secondary tympanic membrane)

Question 51

____ ______ lines the lateral wall of cochlear duct. It is a highly ____ and slightly _____ structure that produces most of the _____ of the ______ labyrinth.

Answer 51

stria vascularis lines the lateral wall of cochlear duct. It is a highly vascular and slightly pigmented structure that produces most of the endolymph of the membranous labyrinth.

Question 52

The ____ __ _____ of the cochlea receives & transmits information of _____(hearing) to the _____.

Answer 52

The organ of Corti of the cochlea receives & transmits information of sound (hearing) to the CNS.

Question 53

The neuroepithelial _____cells of the organ of corti are _____cells.

Answer 53

The neuroepithelial receptor cells of the orga of corti are hair cells.

Question 54

Hair cells arranged in 2 groups:

• _____ hair cells: form ____ _____ from base to apex of cochlea
• ____ hair cells: increase from ____ rows at _____of cochlea to ____rows at _____.

Answer 54

Hair cells arranged in 2 groups:

• Inner hair cells: form single row from base to apex of cochlea
• Outer hair cells: increase from 3 rows at base of cochlea to 5 rows at apex

Question 55

Cochlear hair cells bear only _____ and no ______ on their free apical surfaces.

Answer 55

Cochlear hair cells bear only stereocilia and no kinocilia on their free apical surfaces.

Question 56

_______ membrane: gelatinous arm that extends over _______ cells; tips of _____are embedded in (or brush) _____membrane

Answer 56

Tectorial membrane: gelatinous arm that extends over hair cells; tips of stereocilia are embedded in (or brush) tectorial membrane

Question 57

Stereocilia are ______: longest stereocilium is located on _____ part of cell; as one moves ___, stereocilia become _____

Answer 57

Stereocilia are polarized: longest stereocilium is located on outer part of cell; as one moves inward, stereocilia become shorter

Question 58

Outward deflection of stereocilia (toward ____ stereocilium or toward ___ _______ causes _____ of the hair cell

Answer 58

Outward deflection of stereocilia (toward longest stereocilium or toward stria vascularis) causes depolarization of the hair cell

Question 59

Inward deflection of stereocilia causes _____ of the hair cell

Answer 59

Inward deflection of stereocilia causes hyperpolarization of the hair cell

Question 60

• Vibrations reaching base of stapes are transferred to ____ of ____ ______
• When footplate of stapes moves in, secondary tympanic membrane ____ ____.
• When footplate of stapes moves out, secondary tympanic membrane is ____ ____

Answer 60

• Vibrations reaching base of stapes are transferred to perilymph of scala vestibuli
• When footplate of stapes moves in, secondary tympanic membrane bulges out
• When footplate of stapes moves out, secondary tympanic membrane is drawn inward

Question 61

Walls of cochlear duct are ____: displacement of perilymph by movement of ____ causes _____of _____ membrane.

Answer 61

Walls of cochlear duct are flexible: displacement of perilymph by movement of stapes causes deflection of basilar membrane.

Question 62

Sounds of different frequencies cause waves in basilar membrane with _____amplitude (maximal membrane displacement) at different points along membrane: _____ ______

Answer 62

Sounds of different frequencies cause waves in basilar membrane with maximal amplitude (maximal membrane displacement) at different points along membrane: tonotopic representation

Question 63

• High frequency sounds cause waves of _____amplitude close to _____ of cochlea
• Low frequency sounds cause waves of _____ amplitude close to _____ of cochlea

Answer 63

• High frequency sounds cause waves of maximal amplitude close to base of cochlea
• Low frequency sounds cause waves of maximal amplitude close to apex of cochlea

Question 64

upward movement of basilar membrane stereocilia deflected outward (toward stria vascularis) tension causes _____ of mechanically gated ion channels (selective to __) ____ enters cell _____ of hair cell

Answer 64

upward movement of basilar membrane stereocilia deflected outward (toward stria vascularis) tension causes opening of mechanically gated ion channels (selective to K+) K+ enters cell depolarization of hair cell

Question 65

depolarization opens voltage-sensitive ___channels____enters cell further depolarization and increased ______ __

Answer 65

depolarization opens voltage-sensitive Ca+ channels Ca+ enters cell further depolarization and increased intracellular Ca+

Question 66

increased intracellular Ca+ binding of ______-containing vesicles to cell membrane release of ____ into ____ ___between hair cell and cochlear nerve (afferent) fiber depolarization of afferent fiber action potential transmitted aalong ____ _____ _____.

Answer 66

increased intracellular Ca+ binding of glutamate-containing vesicles to cell membrane release of glutamate into synaptic cleft between hair cell and cochlear nerve (afferent) fiber depolarization of afferent fiber action potential transmitted along cochlear nerve fibers.

Question 67

Type I sensory neurons make up ____% of neurons in the spiral ganglion

peripheral processes synapse with only one ____ ____ ____ (each ____ hair cell is contacted by peripheral processes of approximately 10 type _____ sensory neurons)

most auditory information conveyed to CNS originates from ____ hair cells

Answer 67

Type I sensory neurons make up 90-95% of neurons in the spiral ganglion

peripheral processes synapse with only 1 inner hair cell (each inner hair cell is contacted by peripheral processes of approximately 10 type I sensory neurons)

most auditory information conveyed to CNS originates from inner hair cells

Question 68

Type II sensory neurons

• peripheral processes innervate only ___ ____ ___ each peripheral process divides, sending collateral branches to approximately 10 ____ hair cells
• (each ____ hair cell is contacted by peripheral processes of approximately ___ type ____sensory neurons)

Answer 68

Type II sensory neurons

• peripheral processes innervate only outer hair cells each peripheral process divides, sending collateral branches to approximately 10 outer hair cells
• (each outer hair cell is contacted by peripheral processes of approximately 4 type II sensory neurons)

Question 69

Cochlear nerve also contains efferent fibers from the ____ ____ _____ (in lower pons)

Answer 69

Cochlear nerve also contains efferent fibers from the superior olivary nucleus (in lower pons)

Question 70

•Outer hair cells are directly innervated by ____ fibers

Answer 70

•Outer hair cells are directly innervated by efferent fibers

Question 71

____ hair cells do not receive direct innervation from efferent fibers (type I afferent fibers receive _____ contacts from ____ fibers just before afferent fibers contact inner hair cells)

Answer 71

Inner hair cells do not receive direct innervation from efferent fibers (type I afferent fibers receive axoaxonic contacts from efferent fibers just before afferent fibers contact inner hair cells)