Chapter 9.3 -Outer and Middle Ear

Question 1

What does the Outer Ear consist of?

Answer 1

Consists of the Pinna and the Ear Canal.

Question 2

What is the Pinna?

Answer 2

Outer-funnel-like part of the ear in which sounds are first collected from the environment. It funnels sound waves into and through the ear canal which extends into the head.

Question 3

What is the Ear Canal?

Answer 3

Conducts sound vibrations from the Pinna to the Tympanic Membrane (ear drum) and prevents damage to the Tympanic Membrane.

Question 4

What is the Tympanic Membrane (ear drum)?

Answer 4

Thin sheet of skin that moves in and out in response to the pressure changes of sound waves. It is the border between the outer ear and middle ear.

Question 5

What are the three tiny bones in the Middle Ear?

Answer 5

Incus and Malleus (connected to the Tympanic Membrane), and Stapes (transmits sound vibrations to the sound window)

Question 6

What is the Oval Window?

Answer 6

The Oval Window is another membrane that borders between the Middle Ear and Inner Ear, through which the Stapes transmits vibrations to the fluid inside the Inner Ear.

Question 7

What is the Inner Ear?

Answer 7

Hollow cavity in the temporal bone of the skull that includes structures such as the Cochlea and the Semicircular Canals of the Vestibular System.

Question 8

What are the two ways the osscile amplify sound vibrations?

Answer 8

Lever action and Concentration of Energy

Question 9

Lever Action

Answer 9

The joints between the ossicles work like levers. When a little bit of energy is applied on one side of the joint, it becomes bigger on thie other side, like a seesaw. This makes the pressure change in the middle ear larger, by about a third, helping us hear softer sounds better.

Question 10

Concentration of Energy

Answer 10

The ossicles also help by concentrating energy from a larger area (tympanic membrane) to a smaller area (oval window). This magnifies the pressure on the oval window

Question 11

What is the role of amplification in our ability to hear faint sounds?

Answer 11

Amplification, achieved through mechanical advantages (levrage and differnet surface areas) in the middle ear, magnifies faint sound vibrations, allowing them to be detected by the fluid-filled chambers in the inner ear, thus enhancing our ability to hear faint sounds.

Question 12

Why does the fluid in the inner ear create a mismatch?

Answer 12

Because it takes more energy to move liquid than air, resulting in minimal movement of the oval window and the liquid behind it if sound waves were transmitted directly to the oval window.

Question 13

What would happen if sound waves were transmitted directly to the oval window?

Answer 13

If we sent sound waves straight to the oval window, they would bounce back because the liquid in our ear needs more energy to move than air. This means the oval window and the liquid wouldn’t move much, and we wouldn’t be able to hear faint sounds very well.

Question 14

What are the two muscles of the middle ear?

Answer 14

Tensor tympani
Stapedius

Question 15

What bone is each muscle attached to
Tensor tympani - malleus
Stapedius - stapes

Answer 15

Tensor tympani - malleus
Stapedius - stapes

Question 16

Tensor tympani Function

Answer 16

Tightens the eardrum to reduce the amount of sound that reaches the inner ear

Question 17

Stapedius Muscle Function

Answer 17

Helps to stabilize a tiny bone in the ear called the stapes, which is involved in transmitting sound.

Question 18

Functions of the muscles together

Answer 18

1) Work to dampen loud noises and protect our ears from potential damage
2)Muscles of middle ear are also tensed during swallowing, talking and general body movement to help keep the auditory system from being overwhelmed by sounds generated by our own body

Question 19

Acoustic Reflex

Answer 19

Protects the ear from intense sounds via contraction of the stapedius and tensor tympani muscles, can protect against abrupt loud sounds such as firing of a gun