4- Ear

Question 1

Ear Dual functions;

Answer 1

Maintain the balance of the body (vestibular)
Perceives sound (Auditory)

Question 2

Ear 3 divisions

Answer 2

3 divisions:
External
Middle
Internal

Question 3

External ear:

Answer 3

The most superficial portion of the ear, the external ear includes the auricle, the external acoustic meatus, and the tympanic membrane
Helps to gather sound and direct it to the tympanic membrane

Question 4

Tympanic cavity –

middle ear

Answer 4

air space within temporal bone (~ 10 x 10 x 6 mm)
Serves as relay center for sound waves
2 continuous regions

Question 5

Tympanic cavity proper =

middle ear

Answer 5

medial to tympanic membrane

Question 6

MIddle ear

Epitympanic recess* =

Answer 6

superior to tympanic membrane

Question 7

Auditory tube & Aditus

Answer 7

Superiorly the epitympanic recess is continuous with the aditus of the mastoid antrum

Question 8

Middle Ear Cavity: relationships: Anteriorly – leads to

Answer 8

auditory (Eustachian) tube

continues to nasopharynx

Question 9

Middle Ear Cavity: relationships: Posteriorly – leads to

Answer 9

aditus ad antrum

Question 10

Middle Ear Cavity: relationships: Epitympanic recess =

Answer 10

superior to tympanic membrane

Question 11

Middle Ear Cavity: relationships: Serves as relay center for

Answer 11

sound waves between external & internal ear

Question 12

Auditory tube

Answer 12

Anterior 2/3: cartilaginous & Posterior 1/3: bony (osseous)
~36 mm long
Cartilaginous & bony portions meet at narrow isthmus

Question 13

Bony portion of auditory tube opens

Answer 13

at base of skull

Question 14

Auditory tube

Only

Answer 14

superior & Medial walls cartilaginous

Inferior & Lateral walls membranous

Question 15

Middle Ear: Jugular wall (floor): Formed by thin plate of

Answer 15

tympanic portion of the temporal bone

Question 16

Middle Ear: Jugular wall (floor): Separates the middle ear cavity from

Answer 16

the jugular fossa

Question 17

Middle Ear: Jugular wall (floor): Fossa contains the

Answer 17

superior jugular bulb of the IJV

Question 18

Promontory =

Answer 18

protuberance facing tympanic membrane

Question 19

Fenestra vestibuli =

Answer 19

oval window – receives base of stapes

Question 20

Fenestra Cochlea =

Answer 20

round window – membrane covered, inferior to oval

Question 21

Middle ear tympanic cavity

Answer 21

Facial canal prominence

Lateral semicircular canal prominence

Tendon of the tensor tympani m.

Question 22

Middle Ear: Carotid wall (Ant.): Formed by

Answer 22

thin plate of tympanic portion of the temporal bone

Question 23

Middle Ear: Carotid wall (Ant.): Separates the middle ear cavity from the

Answer 23

carotid canal

Question 24

Middle Ear: Carotid wall (Ant.): 2 openings present in the

Answer 24

superior aspect
Auditory tube
Semicanal for tensor tympani m.

Question 25

MIddle ear mastoid wall: Pyramidal Eminence =

Answer 25

hollow projection of bone | Serves as origin of stapedius m.

Question 26

MIddle ear mastoid wall: Aditus ad antrum =

Answer 26

entrance to tympanic antrum | Leads to post./infr. into mastoid air cells

Question 27

Middle Ear: Muscles

Answer 27

Tensor tympani m. | Stapedius m.

Question 28

Middle Ear: Muscles: Act to reduce

Answer 28

oscillations of ossicles

Question 29

Middle Ear: Muscles: Protects inner ear from

Answer 29

injury during loud noises

Question 30

Tensor tympani m.

Answer 30

Contained in bony semicanal Superior to auditory tube Runs posterior thru canal & then bends laterally Inserts onto handle of malleus Tenses tympanic membrane by drawing it medially Innervated by CN V3

Question 31

Stapedius m.

Answer 31

``` Smallest striated m. in body ~ 1 mm Arises from cavity inside pyramidal eminence Inserts into neck of stapes Pulls head of stapes posteriorly Innervated by CN VII ``` Acts to reduce oscillations of ossicles Protects inner ear from injury during loud noises

Question 32

Middle Ear: Vessels: Arterial supply via tympanic branches of

Answer 32

carotid branches Anterior tympanic, inferior tympanic, superior tympanic, stylomastoid, & caroticotympanic aa.

Question 33

Middle Ear: Vessels: Venous drainage via accompanying

Answer 33

vv. Drain to superior petrosal sinus or Pterygoid plexus of vv.

Question 34

All tympanic brs. are too

Answer 34

tiny to dissect

Question 35

Middle Ear: Facial nerve (CN VII) & Facial canal: CN VII enters

Answer 35

facial canal & runs posteriorly

Question 36

Middle Ear: Facial nerve (CN VII) & Facial canal: Travels in

Answer 36

medial wall of middle ear

Question 37

Middle Ear: Facial nerve (CN VII) & Facial canal: Canal passes over

Answer 37

oval window & turns inferiorly Then passes behind the round window

Question 38

Middle Ear: Facial nerve (CN VII) & Facial canal: Canal Continues inferiorly to exit at the

Answer 38

stylomastoid foramen

Question 39

Chorda tympani

Answer 39

Ascends anteriorly thru middle ear cavity Crosses medial surface of tympanic membrane Passes between handle of malleus & incus Exits cavity thru anterior iter chordae to petrotympanic fissure Ultimately descends with Lingual n. into oral cavity

Question 40

Middle Ear: Greater Petrosal N.: Br. off

Answer 40

geniculate ganglion of CN VII

Question 41

Middle Ear: Greater Petrosal N.: Carries p-symp. fibers to

Answer 41

pterygopalatine ganglion

Question 42

Middle Ear: Greater Petrosal N.: Joins deep petrosal n. (symp.) to form

Answer 42

n. of pterygoid canal

Question 43

Middle Ear: Greater Petrosal N.: Runs from hiatus of greater petrosal n. to

Answer 43

pterygoid canal | From petrous temporal toward foramen lacerum

Question 44

Middle Ear: Tympanic Plexus of nn.: Covers promontory in

Answer 44

middle ear cavity

Question 45

Middle Ear: Tympanic Plexus of nn.: Runs under mucosal lining of

Answer 45

cavity and supplies it

Question 46

Middle Ear: Tympanic Plexus of nn.: Supplies

Answer 46

mastoid air cells and auditory tube

Question 47

Middle Ear: Tympanic Plexus of nn.: Formed by tympanic br. of

Answer 47

CN IX (p-symp.)

Question 48

Middle Ear: Tympanic Plexus of nn.: Formed by

Answer 48

cartoticotympanic nn. (symp.)

Question 49

Middle Ear: Lesser Petrosal N.: Br. of

Answer 49

tympanic plexus from CN IX

Question 50

Middle Ear: Lesser Petrosal N.: Continuation of

Answer 50

tympanic br. of CN IX

Question 51

Middle Ear: Lesser Petrosal N.: Carries p-symp. fibers to

Answer 51

otic ganglion (supplies parotid gl.)

Question 52

Middle Ear: Lesser Petrosal N.: Runs from hiatus of

Answer 52

lesser petrosal n. to foramen ovale | Otic ganglion located below foramen ovale (medially)

Question 53

Otic ganglion supplies

Answer 53

p-symp. fibers to the parotid gland

Question 54

Internal Ear duel functions

Answer 54

``` Maintain the balance of the body (vestibular) Perceives sound (Auditory) ```

Question 55

Internal Ear: Fluid-filled chamber for

Answer 55

hearing & equilibrium

Question 56

Internal Ear: Semicircular canals –

Answer 56

controls balance & position

Question 57

Internal Ear: Cochlea – controls

Answer 57

hearing

Question 58

Internal Ear: Oval window – beginning of

Answer 58

cochlea (receives stapes)

Question 59

Internal Ear: Round window – end of

Answer 59

cochlea (closed by membrane) | Vibrates opposite oval window to perceive sound

Question 60

Round window vibrates opposite the

Answer 60

oval window to perceive sound