Unit Three: Equilibrium and Hearing

Question 1

What are the three anatomical regions of the ear?

Answer 1

1. External ear. 2. Middle ear. 3. Internal ear.

Question 2

What anatomical region of the ear contains the sensory organs for equilibrium (balance) and hearing?

Answer 2

The internal ear.

Question 3

What does the external ear include? (2)

Answer 3

1. The outer fleshy auricle. 2. External acoustic meatus.

Question 4

What does the auricle protect? What does it provide?

Answer 4

The opening passageway and provides directional sensitivity to the ear by directing sound inward toward the tympanic membrane.

Question 5

What is the tympanic membrane? What does it separate?

Answer 5

The eardrum. It is thin, semitransparent connective tissue separating the external ear from the middle ear.

Question 6

What do ceruminous glands secrete?

Answer 6

Cerumen.

Question 7

What does cerumen do?

Answer 7

Slows the growth of microorganisms and reduces the chance of infection.

Question 8

What are ceruminous glands modifications of?

Answer 8

Sweat glands.

Question 9

What does the middle ear consist of?

Answer 9

The tympanic cavity, which contains auditory ossicles.

Question 10

What is the tympanic cavity?

Answer 10

An air-filled space that contains auditory ossicles.

Question 11

What does the tympanic cavity communicate with? (2)

Answer 11

The nasopharaynx through the auditory canal. 2. Mastoid air cells.

Question 12

Where does the auditory tube penetrate?

Answer 12

The petrous part of the temporal bone.

Question 13

What is the auditory tube also called?

Answer 13

Eustachian tube.

Question 14

What does the auditory tube do?

Answer 14

It helps equalize the pressure in the middle ear with external, atmospheric pressure.

Question 15

What do the three bones comprising the auditory ossicles do?

Answer 15

They connect the tympanic membrane with the receptor complex of the internal ear.

Question 16

What are the three auditory ossicles connected by? What do they do?

Answer 16

Synovial joints. They transfer sound vibrations from the tympanic membrane to a fluid-filled chamber within the internal ear.

Question 17

What are the three auditory ossicles?

Answer 17

1. Malleus. 2. Incus. 3. Stapes.

Question 18

What is the oval window?

Answer 18

A hole in the bony wall of the middle ear cavity.

Question 19

What does vibration of the tympanic membrane do?

Answer 19

It converts arriving sound waves into mechanical movements.

Question 20

Describe the vibration of the auditory ossicles.

Answer 20

The malleus vibrates the incus. The incus vibrates the stapes.

Question 21

What does the movement of the stapes do?

Answer 21

It causes vibrations in the fluid contents of the internal ear.

Question 22

What is the auricle of the external ear made up of?

Answer 22

Elastic cartilage.

Question 23

What two muscles reduce movements of the auditory ossicles in the ear?

Answer 23

1. Tensor tympani muscle. 2. Stapedius muscle.

Question 24

What muscle equalizes pressure?

Answer 24

Levator veli palatini.

Question 25

What are the two divisions of the inner ear?

Answer 25

1. Bony labyrinth. 2. Membranous labyrinth.

Question 26

What does the bony labyrinth contain?

Answer 26

Perilymph.

Question 27

What does the membranous labyrinth contain?

Answer 27

Endolymph.

Question 28

Is perilymph and endolymph a byproduct of cerebrospinal fluid?

Answer 28

Yes.

Question 29

What are the layers of the inner ear (from outside-in)? (4)

Answer 29

1. Bony labyrinth. 2. Perilymph. 3. Membranous labyrinth. 4. Endolymph.

Question 30

What can the membranous labyrinth be divided into? (2)

Answer 30

1. Cochlear duct (hearing). 2. Vestibular complex (equilibrium).

Question 31

What can the vestibular complex include? (2)

Answer 31

1. Semicircular ducts (rotation). 2. Utricle and saccule (gravity and linear acceleration).

Question 32

Where do high frequency sounds stimulate the spiral organ?

Answer 32

More proximal to the oval window.

Question 33

Where do low frequency sounds stimulate the spiral organ?

Answer 33

Closer to the apex of the cochlea.

Question 34

What 3 channels are the cochlea divided into?

Answer 34

1. Scala vestibuli. 2. Scala tympani. 3. Cochlear duct.

Question 35

What does the spiral organ detect?

Answer 35

Endolymph movement.

Question 36

What is the tectorial membrane?

Answer 36

The overlying gelatinous mass the stereocilia project into.

Question 37

Where does the spiral organ sit?

Answer 37

On the basement membrane.

Question 38

What do spiral organs contain?

Answer 38

Thick sensory epithelium with hair cells.

Question 39

Describe the path of sound waves through the ear (1-4).

Answer 39

1. Tympanic membrane. 2. Auditory ossicles. 3. Oval window. 4. Scala vestibuli.

Question 40

Describe the path of sound waves through the ear from the scala vestibuli (3).

Answer 40

1. Cochlear duct. 2. Scala tympani. 3. Round window.

Question 41

In what Brodmann's area is the primary auditory cortex?

Answer 41

41, 42.

Question 42

Describe the first 3 steps of the CNS pathway of audition.

Answer 42

1. Basilar membane. 2. Cochlear part of CN VIII. 3. Brainstem nuclei (Cochlear nucleus).

Question 43

Describe the second 3 steps of the CNS pathway of audition.

Answer 43

1. Medial geniculate nucleus (thalamus). 2. Primary auditory cortex. 3. Auditory association cortices.

Question 44

What does the utricle allow for?

Answer 44

An understanding of horizontal movement.

Question 45

What does the saccule allow for?

Answer 45

An understanding of vertical movement.

Question 46

What is the macula of the utricle and saccule?

Answer 46

The portion of the above regions that contain hair cells.

Question 47

What are stereocilia and kinocilia embedded in?

Answer 47

A gelatinous layer covered in otoliths.

Question 48

What are the three semicircular canals/ducts?

Answer 48

1. Anterior. 2. Posterior. 3. Lateral.

Question 49

What is the ampulla?

Answer 49

The expanded region of each semicircular canal.

Question 50

What is the cupula?

Answer 50

The overlying gelatinous dome that stereocilia and kinocilia are embedded into.

Question 51

What semicircular duct is sensitive to "yes?"

Answer 51

Anterior.

Question 52

What semicircular duct is sensitive to "no?"

Answer 52

Lateral.

Question 53

What semicircular duct is sensitive to "tilting head?"

Answer 53

Posterior.

Question 54

What happens when the head rotates?

Answer 54

The endolymph moves and pushes against the cupula and bends the stereocilia.

Question 55

Describe the CNS pathway for vestibulation (2).

Answer 55

1. Vestibular part of CN VIII. 2. Vestibular nuclei (medulla).

Question 56

What occurs in the CNS pathway for vestibulation once the sensory info reaches the medulla? (2)

Answer 56

1. Integration of sensory info. 2. Info gets relayed to cerebellum, cerebral cortex, spinal cord, CN III, IV, VI, XI.

Question 57

What nerves receive information from the vestibulation pathway? (4)

Answer 57

1. III. 2. IV. 3. VI. 4. XI.

Question 58

Describe the path of where vestibular nuclei relay information (4).

Answer 58

1. Cerebellum. 2. Motor nuclei of the extra-ocular muscle of the eye. 3. Cerebral cortex to provide conscious sens of position and movement. 4. To other motor nuclei in the brainstem and spinal cord.