Anatomy of the Inner Ear

Question 1

What imaging modality is the best for assessing disease in middle ear?

Answer 1

CT

Question 2

What are the 3 parts of the ear?

Answer 2

External, Middle, Inner

Question 3

What’s the function of the external ear?

Answer 3

Collects sound waves at the eardrum

Question 4

What’s the function of the middle ear?

Answer 4

Air filled space where vibrations of tympanic membrane are transmitted by 3 ossicles.

Question 5

What’s the function of the inner ear?

Answer 5

Membranous filled sac containing receptor cells

Question 6

What type of slices are required for imaging of the ear? And what 2 planes are used?

Answer 6

Thin

Axial & coronal

Question 7

The petrous bone is positioned in an _____ orientation from posterolateral to ______

Answer 7

oblique

anteromedial

Question 8

What direction would structures be sectioned on coronal images?

Answer 8

obliquely

Question 9

What plane is useful to visualise the length of the ear canal?

Answer 9

Off coronal plane

Question 10

What 2 structures does the external ear have?

Answer 10

Auricle & External auditory meatus (EAM)

Question 11

Does the EAM extend inwards or outwards to the tympanic membrane?

Answer 11

Inwards

Question 12

How long is the EAM and what shape course does it follow?

Answer 12

3.7cm long

S-shaped

Question 13

The EAM outer lateral portion is ______

Answer 13

Cartilaginous

Question 14

What 2 types of glands does the overlying skin of the EAM contain? (C__ & S__)

Answer 14

Ceruminous & sebaceous

Question 15

What does the tympanic membrane do?

Answer 15

Separates middle ear from the EAM

Question 16

Less than __mm in greatest diameter, the tympanic membrane faces laterally _____ & _____

Answer 16

12

downwards & forwards

Question 17

What’s the name of the bony spur formed by the lateral wall of the tympanic cavity & superior wall of EAM.

Answer 17

Scutum

Question 18

Cholesteatoma is formed by the ____ retraction of the pars _____ of the tympanic membrane into the epitympanum

Answer 18

medial

flaccida

Question 19

What part of the temporal bone is the tympanic cavity/ middle ear located?

Answer 19

Petrous part

Question 20

Whats the name of the 3 auditory ossicles the tympanic cavity contains?

Answer 20

Malleus, incus, stapes

Question 21

The lateral wall of the tympanic cavity is formed by the ______ _____ and above this by the ____ part of temporal bone

Answer 21

tympanic membrane

squamous

Question 22

What is the name of the part of the cavity above the tympanic membrane and what 2 ossicles does it contain?

Answer 22

epitympanic recess/ attic

incus & head of malleus

Question 23

What is the medial wall of the middle ear?

Answer 23

Round window

Question 24

The round window is closed by the second tympanic membrane: _____ ______ or ___ window occupied by the base of the _____, the _____ formed by the first part of the cochlea & the prominence caused by the underlying canal for the _____ nerve

Answer 24

fenestra vestibuli
oval
stapes
promontory
facial

Question 25

What structure is attached to the base of the cochlea in the oval window?

Answer 25

Stapes footplate

Question 26

What are the boundaries of the middle ear? Lateral Medial Superior

Answer 26

Lateral: tympanic membrane Medial: Round window Superior: epitympanic recess/ attic

Question 27

Which is the largest of the 3 ossicles?

Answer 27

Malleus

Question 28

The malleus has a handle attached to the _____ membrane, a rounded head which articulates with the ___ & a lateral process

Answer 28

tympanic | incus

Question 29

What 3 parts does the malleus have?

Answer 29

Head, neck & 3 processes

Question 30

List the 3 processes of the malleus

Answer 30

1. manubrium (handle) 2. anterior process 3. lateral process

Question 31

Which 2 of the 3 processes of the malleus are attached to the tympanic membrane?

Answer 31

manubrium & lateral process

Question 32

What appearance does the malleus give in axial CT?

Answer 32

Ball of ice cream on a cone

Question 33

How many parts does the incus have?

Answer 33

3 - body & 2 processes

Question 34

What does the base of the stapes do?

Answer 34

Seals the oval window and conducts vibrations to the cochlea.

Question 35

The base of the stapes is attached to the neck via what 2 structures?

Answer 35

Anterior & posterior arches

Question 36

What's the name given to the concave head of the stapes?

Answer 36

Capitulum

Question 37

The concave head of the stapes articulates with the ______ nodule of the incus

Answer 37

lentiform

Question 38

The malleus articulates to what 2 structures?

Answer 38

Tympanic membrane & incus

Question 39

The round window Is closed off from the middle ear by what?

Answer 39

The round window membrane

Question 40

What's the function of the round window?

Answer 40

It allows fluid from the cochlea to move so that hair cells of the basilar membrane are stimulated and audition can occur.

Question 41

How does the round window serve as a release valve?

Answer 41

It dissipates the pressure generated by the fluid vibrations in the cochlea

Question 42

Where is the round window situated?

Answer 42

Below and behind the oval window .

Question 43

Whats another name for the attic/upper portion of tympanic cavity?

Answer 43

Epitympanum

Question 44

What does the epitympanum contain?

Answer 44

Head of malleus & body of incus

Question 45

Whats the best plane to view the epitympanum?

Answer 45

Coronal CT

Question 46

What do you call the portion of the middle ear cavity below the floor of the EAM?

Answer 46

Hypotympanum

Question 47

Where do the mastoid air cells lie and open into?

Answer 47

Within the mastoid processes & open into mastoid anthrum

Question 48

What does the inner ear consist of?

Answer 48

vestibule, cochlea, semicircular ducts

Question 49

The vestibule and semicircular canals are responsible for what?

Answer 49

Balance

Question 50

What's the cochlea responsible for?

Answer 50

Hearing

Question 51

Where is the vestibule located?

Answer 51

Medial to the oval window

Question 52

What 2 structures is the vestibule composed of?

Answer 52

Utricle (posterosuperiorly) & Saccule (inferiorly)

Question 53

What does the utricle communicate with?

Answer 53

Semicircular canals

Question 54

What does the saccule communicate with? and via what? (D____ R____)

Answer 54

Cochlear duct | via ductus reuniones

Question 55

What shape is the cochlea?

Answer 55

Snail-shaped

Question 56

The base corresponds with the bottom of the _____ _____ meatus & is perforated by a number apertures for the passage of the cochlear division of the ______ nerve.

Answer 56

Internal acoustic | Acoustic

Question 57

What's the central axis of the cochlea called?

Answer 57

modiolus

Question 58

The o_____ s_____ l____ subdivides the canal into 2 passages.

Answer 58

osseous spiral lamina

Question 59

What's another name for cochlear aqueduct?

Answer 59

Cochlea canaliculus

Question 60

What lymphatic duct does the cochlear aqueduct contain?

Answer 60

Perilymphatic duct

Question 61

The perilymphatic duct connects with what part of the cochlea with the subarachnoid space? (S____ T____)

Answer 61

Scala tympani

Question 62

Where does the cochlear aqueduct open into the subarachnoid space? (something of the jugular foramen? (p__ n____)

Answer 62

Beside the pars nervosa of the jugular foramen

Question 63

Where does the cochlear nerve lie In the internal acoustic canal?

Answer 63

Anteroinferior portion

Question 64

Where does the cochlear nerve enter prior the spiral ganglia? (m____)

Answer 64

Modiolus

Question 65

The upper portion of the posterior semicircular canal forms a common canal ( c____ c___) with the s____ s____ c____ before opening into vestibule

Answer 65

Common crus | Superior semicircular canal

Question 66

The eustachian cavity is a communication between what 2 structures?

Answer 66

Middle ear cavity & nasopharynx

Question 67

What's the purpose of the eustachian canal?

Answer 67

Allows for aeration & drainage

Question 68

What's the purpose of the Eustachian tube?

Answer 68

Allows the middle ear to normalise with atmospheric pressure

Question 69

What directions does the eustachian canal extend from the tympanic cavity?

Answer 69

Downwards, forwards & medially

Question 70

The carotid canal is a passageway in the ____ bone through which the ____ ___ ___ enters the middle cranial fossa from the neck.

Answer 70

Temporal | Internal carotid artery

Question 71

Whats the facial nerve responsible for?

Answer 71

Motor function of muscles of facial expression Stapedius muscle sensation of the skin of ear taste for ant. 2/3 tongue

Question 72

What are the contents of the Internal auditory canal/ meatus

Answer 72

``` Facial nerve (CN VII|) Segments of vestibulocochlear nerve (CN VIII) ```

Question 73

What canal does the facial nerve leave the IAM?

Answer 73

Fallopian canal