HS2-12 Ear

Question 1

What are the three regions of the ear?

Answer 1

external ear

middle ear

inner ear

Question 2

What is the function of the external ear?

Answer 2

collection of sound waves

Question 3

What is the function of the middle ear?

Answer 3

transduction of sound waves from air to fluid of inner ear

Question 4

What is the function of the inner ear? (3)

Answer 4

hearing

gravity

motion/acceleration

Question 5

What are the three parts of the external ear?

Answer 5

auricle

external acoustic meatus

tympanic membrane

Question 6

What is the composition of the auricle?

Answer 6

cartilaginous skeleton

Question 7

The cartilaginous skeleton of the auricle is continuous with

Answer 7

the cartilage of the external acoustic meatus

Question 8

What are the boundaries of the external acoustic meatus?

Answer 8

auricle → tympanic membrane

Question 9

What is the tympanic membrane?

Answer 9

boundary between the external and middle ears

Question 10

Why is the tympanic membrane actually not flat?

Answer 10

depressed inward by its attachment to malleus

Question 11

What structures can be seen through the tympanic membrane?

Answer 11

manubrium (handle of malleus)

chorda tympani (from CN VII)

Question 12

What is the best place for an incision in the tympanic membrane?

Answer 12

posterior-inferiorly, away from the chorda tympani and ossicles

Question 13

What are the components of the middle ear?

Answer 13

tympanic cavity

tympanic antrum

pharyngotympanic tube

Question 14

What is the lateral boundary of the middle ear?

Answer 14

tympanic membrane

Question 15

The middle ear opens anteriorly into

Answer 15

the pharynx, via the pharyngotympanic tube

Question 16

The middle ear opens posteriorly into

Answer 16

mastoid air cells

Question 17

What are the three middle ear ossicles? Indicate their relative sizes and positions.

Answer 17

malleus (largest, most lateral)

incus (middle)

stapes

Question 18

List the four structures associated with the malleus. (4)

Answer 18

head of malleus

manubrium of malleus = handle

tensor tympani muscle

chorda tympani nerve

Question 19

Describe the position of the manubrium of the malleus.

Answer 19

embedded in tympanic membrane

Question 20

Describe the position of the tensor tympani relative to the malleus.

Answer 20

attaches to manubrium of malleus

Question 21

Describe the position of the chorda tympani relative to the malleus.

Answer 21

passes just medially to the manubrium and tympanic membrane

Question 22

What are the three structures associated with incus?

Answer 22

body of incus

long limb

short limb

Question 23

What does the body of the incus do?

Answer 23

articulates with head of malleus

Question 24

What does the long limb of the incus do?

Answer 24

articulates w/ stapes at distal tip

Question 25

What does the short limb of the incus do?

Answer 25

attaches to posterior wall of middle ear via ligament

Question 26

What are the four structures associated with the stapes?

Answer 26

head to stapes neck of stapes two limbs base

Question 27

What does the head of the stapes do?

Answer 27

articulates with long limb of incus

Question 28

What does the neck of the stapes do?

Answer 28

receives insertion of stapedius muscle

Question 29

What do the two limbs of the stapes do?

Answer 29

the two limbs (anterior and posterior) extend to base

Question 30

What does the base of the stapes do?

Answer 30

presses into oval window

Question 31

What is the function of the ossicles?

Answer 31

transmit airborne sound waves or vibrations to aqueous medium of inner ear

Question 32

How do the ossicles transmit sound waves to the aqueous humor of the inner ear?

Answer 32

act as pressure transducers to overcome different densities of air and water

Question 33

What is the function of the stapedius?

Answer 33

restricts movement of ossicles, thus dampening loud sounds

Question 34

Where is the stapedius located?

Answer 34

pyramidal eminence

Question 35

The stapedius is innervated by

Answer 35

CN VII

Question 36

Where is the tensor tympani found in the ear?

Answer 36

in the pharyngotympanic/auditory tube

Question 37

The tensor tympani is innervated by

Answer 37

CN V₃

Question 38

What are the two series of canals found in the inner ear?

Answer 38

bony labyrinth membranous labyrinth

Question 39

List the features of the inner ear. (2)

Answer 39

small completely encased in bone

Question 40

The bony labyrinth of the ear is filled with

Answer 40

perilymph

Question 41

How is the bony labyrinth connected to the middle ear?

Answer 41

via fenestra vestibuli (oval window) and fenestra cochlea (round window)

Question 42

What are the three regions of the bony labyrinth?

Answer 42

vestibule cochlea 3 semicircular canals

Question 43

What are the three semicircular canals?

Answer 43

anterior posterior lateral

Question 44

Describe the positioning of the three semicircular canals.

Answer 44

all at right angles to each other

Question 45

What is an ampulla (of the ear)?

Answer 45

an osseous structure at which a semicircular canal gets dilated

Question 46

The membranous labyrinth is filled with

Answer 46

endolymph

Question 47

What are the four components of the membranous labyrinth?

Answer 47

utricle saccule semicircular ducts cochlear duct

Question 48

What is the utricle?

Answer 48

large fluid filled sac that is attached to each semicircular canal

Question 49

What is the saccule?

Answer 49

smaller fluid filled sac that is attached to cochlea

Question 50

Give two examples of structures in the ear that are sensitive to changes in gravity.

Answer 50

utricle saccule

Question 51

What are the semicircular ducts (of the ear)?

Answer 51

fluid filled tubes inside each of the bony canals

Question 52

What is the cochlear duct?

Answer 52

fluid filled tube inside bony cochlea

Question 53

The bony cochlea is divided into what two spaces?

Answer 53

scala vestibuli (from fenestra vestibuli) scala tympani (fenestra cochlea)

Question 54

Sound sensitive hair cells are located in

Answer 54

the cochlear duct

Question 55

The facial nerve exits the cranial cavity via

Answer 55

the internal acoustic meatus

Question 56

What is the geniculate ganglion?

Answer 56

sensory ganglion associated with the facial nerve

Question 57

What are the four branches of the facial nerve within the temporal bone?

Answer 57

greater petrosal nerve nerve to stapedius chorda tympani motor nerves to muscles of facial expression

Question 58

CN IX exits the cranial cavity via

Answer 58

the jugular foramen

Question 59

The tympanic branch of CN IX re-enters the skull through

Answer 59

the floor of the middle ear cavity

Question 60

What are the branches of CN IX within the temporal bone? (2)

Answer 60

sensory nerves lesser petrosal nerve

Question 61

What separates the bony and membranous labyrinths?

Answer 61

perilymph

Question 62

How is balance sensed by the ear?

Answer 62

relative movement of fluids within the 3 semicircular canals

Question 63

Describe the propagation of sound in the inner ear. (5)

Answer 63

oval window (from ossicles) scala vestibuli scala tympani round window as sound travels, it vibrates basilar membrane, which is what sends signals to the brain for hearing

Question 64

What are the vessels found in the temporal bone? (3)

Answer 64

internal carotid artery internal jugular vein sigmoid sinus

Question 65

List the pathway of sound through the external ear.

Answer 65

auricle (pinna) funnels sound through the ↓ external acoustic meatus, to the ↓ tympanic membrane

Question 66

What provides general sensory innervation to the external ear? Draw a diagram. (4)

Answer 66

lesser occipitial (C2, C3) = posterior tip of external ear/auricle great auricular (C2, C3) = auricle + earlobe auricular branch of CN X = inferior portion of external acoustic meatus auriculotemporal nerve (CN V3) = superior portion of external acoustic meatus

Question 67

Label the following diagram of the pinna/auricle.

Answer 67

Question 68

What is cauliflower ear?

Answer 68

hematoma between skin and cartilaginous skeleton

Question 69

The cartilaginous portions of the ear houses what glands? (2)

Answer 69

ceruminous (wax) glands sebaceous (oil) glands

Question 70

Describe the pathway of sound vibrations in the middle ear.

Answer 70

tympanic membrane ↓ malleus ↓ incus ↓ stapes ↓ oval window

Question 71

The tensor tympani attaches to what bone?

Answer 71

malleus

Question 72

What muscle is responsible for opening the auditory/Eustachian tube?

Answer 72

tensor veli palatini, a muscle of the palate

Question 73

What is the innervation of the tensor veli palatini?

Answer 73

CN V₃

Question 74

Broadly speaking, the semicircular canals are responsible for what function?

Answer 74

balance

Question 75

Broadly speaking, the utricle is responsible for what function?

Answer 75

horizontal motion

Question 76

Broadly speaking, the saccule is responsible for what function?

Answer 76

vertical motion

Question 77

Describe the pathway of sound vibrations in the inner ear.

Answer 77

oval window (fenestra vestibuli) ↓ scala vestibuli ↓ scala tympani ↓ round window (fenestra cochlea)

Question 78

What is the primary sensory structure located within the cochlea? Describe its function.

Answer 78

organ of Corti - its specialized hair cells sense vibrations of the basilar membrane, which are induced by fluid waves moving through scala vestibuli and scala tympani