Audition

Question 1

What is the function of the external (outer) ear?

Answer 1

It collects sound waves and passes them inwards

Question 2

What structures make up the external ear? Describe them if applicable

Answer 2

Auricle/Pinna- Cartilage covered with skin
External auditory canal/acoustic meatus
Tympanic membrane or eardrum-Skin and CT

Question 3

True or False: The auricles of most animals are large and can be oriented in different directions?

Answer 3

True

Question 4

What are the ear ossicles? (describe and name them)

Answer 4

Small bones in the tympanic cavity
Malleus, uncus, stapes

Question 5

What is the function of the ear ossicles?

Answer 5

Transmit vibrations of the eardrum to the oval window

Question 6

True or False: The functions of the ear ossicles are enhanced by the tensor tympani and the stapedius muscles?

Answer 6

False- They are dampened

Question 7

What is the purpose of damping muscles?

Answer 7

CNS control over sensory input to protect the auditory receptor cells. Innervated by cranial nerves

Question 8

What is the bony labyrinth?

Answer 8

Tortuous channels that go through the temporal bone
contain the vestibule, cochlea, and semicircular canals
Filled with perilymph

Question 9

What is the membranous labyrinth?

Answer 9

Series of membranous sacs withing the bony labyrinth
Filled with endolymph- potassium rich fluid

Question 10

What is the structure of the vestibule?

Answer 10

Central egg-shaped cavity of the bony labyrinth
Suspended in it’s perilymph are two sacs

Question 11

What is the function on the sacs of the vestibule?

Answer 11

House equilibrium receptors called maculae
Respond to gravity changes and the position of the head

Question 12

Describe the structure of the semicircular canals.

Answer 12

Three canals that each define two-thirds of a circle and lie in the three planes of space

Membranous semicircular ducts line each canal

The ampulla is the swollen end of each canal and it houses equilibrium receptors in the crista ampullaris

Question 13

What are the three chambers of the cochlea?

Answer 13

Scala vestibuli
Scala media
Scala tympani

Question 14

What is the cochlea?

Answer 14

A spiral, conical, bony chamber
It extends from the anterior vestibule
Coils around a bony pillar called the modiolus
Contains cochlear duct and the organ of corti

Question 15

Where does the cochlear duct end?

Answer 15

Cochlear apex

Question 16

What is the function of the organ of corti?

Answer 16

Hearing receptor

Question 17

Where does the scala tympani terminate?

Answer 17

Round oval window

Question 18

What are the scala tympani and the vestibuli filled with?

Answer 18

Perilymph

Question 19

What makes the scala tympani and the vestibuli continuous with each other?

Answer 19

The helicotrema

Question 20

What is the scala media filled with?

Answer 20

Endolymph

Question 21

What is the floor of the cochlear duct composed of?

Answer 21

Bony spiral lamina
Basilar membrane
The cochlear branch of nerve VIII

Question 22

What supports the organ of Corti?

Answer 22

Basilar membrane

Question 23

Where does the cochlear brain of nerve VIII start and stop?

Answer 23

Organ of cori to the brain

Question 24

What is the route of sound transmission in the outer ear

Answer 24

Pinna -> auditory canal -> eardrum

Question 25

What is the route of transmission of sound to the inner ear?

Answer 25

Scales vestibuli and tympani -> cochlear duct

Question 26

What is the route of sound transmission to the middle ear?

Answer 26

Malleus, incus, stapes to oval window