Lecture 31b

Question 1

Three parts of the ear/vestibulocochlear organ

Answer 1

• external ear
• middle ear
• internal ear

Question 2

External ear parts

Answer 2

• auricle/pinna

- external acoustic meatus

Question 3

Different parts of auricle/pinna

Answer 3

• helix
• antihelix
• concha
• tragus
• antitragus
• lobule

Question 4

In the average adult, how long is the external acoustic meatus?

Answer 4

The canal is about an inch long

Question 5

What directions does the acoustic canal take?

Answer 5

inward –> bends backward –> bends forward and down

Question 6

Where does the external acoustic meatus end?

Answer 6

tympanic membrane

Question 7

How is the acoustic canal divided up?

Answer 7

• outer 1/3 is cartilaginous (secrete cerumen; wider)

- inner 2/3 is bony (NO cerumen; narrower)

Question 8

Middle ear ossicles

Answer 8

• malleus/”hammer” (most lateral)
• incus/”anvil”
• stapes/”stirrup” (most medial)

Question 9

What is the roof of the middle ear called?

Answer 9

tegmen tympani

Question 10

What space is directly INTERNAL to tympanic membrane?

Answer 10

tympanic cavity

Question 11

What space is directly ABOVE the tympanic membrane?

Answer 11

epitympanic recess

Question 12

What is the tympanic membrane composed of?

Answer 12

• skin
• mucous membrane
• connective tissue

Question 13

Which ossicle is attached to the inner side of the tympanic membrane?

Answer 13

malleus

Question 14

Umbo

Answer 14

center-most depressed portion of tympanic membrane

Question 15

Medial wall of middle ear

Answer 15

promontory created by base of the cochlea

Question 16

Two openings associated with promontory

Answer 16

• fenestra vestibuli (oval; receives footplate of stapes)

- fenestra cochlea (round; closed by membrane)

Question 17

Anterior to tympanic membrane

Answer 17

tympanic cavity (contains tensor tympani)

Question 18

Tensor tympani has an opening leading to the…

Answer 18

eustachian/auditory tube

Question 19

Eustachian/auditory tube

Answer 19

• connects middle ear and nasopharynx

- 1/3 bony (auditory end) and 2/3 cartilaginous (nasopharyngeal end)

Question 20

Tubal tonsil

Answer 20

collection of lymphoid tissue in opening of auditory tube in nasopharynx

Question 21

aditus ad antrum (opening to the mastoid antrum)

Answer 21

communicates below and behind tympanic membrane with the mastoid air cells

Question 22

Pyramidal eminence originates with the…

Answer 22

stapedius muscle

Question 23

The 3 ossicles are united by ________ and are suspended in air by ____________

Answer 23

• joints

- their attachments to each other, the tympanic membrane, and the oval window

Question 24

Nerves coursing within the ear

Answer 24

• tympanic plexus (from tympanic branch of CN IX)

- chorda tympani branch of CH VII

Question 25

Internal ear most responsible for...

Answer 25

essential organs for hearing and sense of balance

Question 26

Organs of the internal ear

Answer 26

- cochlear duct (for hearing) - semicircular ducts (for balance and position) - utricle (for balance and position) - saccule (for balance and position)

Question 27

Organs of the internal ear contain a fluid called...

Answer 27

endolymph, which stimulates sensory endings, which stimulates fibers of CN VIII to fire and send info to brain

Question 28

Membranous labyrinth

Answer 28

- composed of semicircular ducts, cochlear duct, utricle, and saccule - contained within bony labyrinth

Question 29

Bony labyrinth components

Answer 29

- cochlea (contains cochlear duct) - vestibule (contains utricle and saccule) - semicircular canals (contains semicircular ducts)

Question 30

Where is perilymph found?

Answer 30

between the bony and membranous labyrinth

Question 31

Cupula

Answer 31

center of cochlea

Question 32

Osseous spinal lamina

Answer 32

along with membranous labyrinth, divides internal cochlea into - scala vestibuli - scala tympani

Question 33

Round (cochlear) window

Answer 33

- allows expansion of fluid upon vibration - covered by a membrane - found at base of cochlea

Question 34

Vestibule location

Answer 34

- middle portion of bony labyrinth - relates to the cochlea lying anteriorly - relates to semicircular canals lying posteriorly

Question 35

Oval (vestibular) window

Answer 35

- opening in lateral vestibular wall | - accommodates the footplate of stapes

Question 36

What do vibrations of the stapes produce?

Answer 36

surges in the fluid of the vestibule

Question 37

Three semicircular canals

Answer 37

- anterior canal - lateral canal - posterior canal

Question 38

Ampulla

Answer 38

- the enlargement where the semicircular canal joins the vestibule - it's through here that the fibers from the vestibular portion of CN VIII pass

Question 39

What lines internal cavity of the bony labyrinth?

Answer 39

membranous labyrinth

Question 40

Membranous labyrinth main function

Answer 40

convert the mechanical energy of the vibrating fluid to electrical energy that can be carried to the brain via CH VIII

Question 41

What forms the membranous part of the bony trochlea?

Answer 41

cochlear duct

Question 42

Cochlear duct is modified into...

Answer 42

- vestibular (Reissner's) membrane | - basilar membrane

Question 43

Basilar membrane modification

Answer 43

spiral organ (of Coti), sensory ending for hearing of CN VIII

Question 44

What forms the membranous part of the bony vestibule?

Answer 44

- utricle | - saccule

Question 45

Utricle and saccule each have a portion of ________, which is responsible for _________

Answer 45

- sensory epithelium | - communicating with vestibular portion of CN VIII for perception of static position sense

Question 46

What is the membranous part of the anterior, posterior, and lateral semicircular canals?

Answer 46

semicircular ducts

Question 47

Ampullary crest

Answer 47

where the fibers from the vestibular portion of CN VIII pass