TOPIC 10

Question 1

What is the visible outer part of the ear called and what is its function?

Answer 1

The auricle. It is designed to capture sound waves and channel them down into the ear canal.

Question 2

Name the different features of the auricle.

Answer 2

The helix, the concha cava, the ear canal and the lobule (ear lobe).

Question 3

What different parts of the ear make up the outer ear.

Answer 3

The ear canal and the auricle (helix, lobule, concha cava)

Question 4

What is another name for the ear drum?

Answer 4

The tympanic membrane.

Question 5

What does the tympanic membrane signify?

Answer 5

The end of the outer ear and beginning of the middle ear.

Question 6

What two functions does the ear have?

Answer 6

Hearing and balance (two of our special senses

Question 7

Summarise the actions of the 3 sections of the ear.

Answer 7

The outer ear receives the sound waves and channels it to the middle ear. The middle ear delivers sound vibrations to the inner ear. The inner ear converts these sound waves into neural impulses so that the brain can interpret the sound.

Question 8

What are the main functions of the outer and middle ear?

Answer 8

They collect sounds and channel them into the inner ear.

Question 9

What separates the outer and middle ear?

Answer 9

The tympanic membrane (ear drum)

Question 10

What comprises the outer ear?

Answer 10

the auricle or pinna (helix, concha cava, lobule) and the external auditory meatus (ear canal).

Question 11

Describe the structure and functions of the external auditory meatus?

Answer 11

EAM leads from the ear canal to the tympanic membrane (so connects the outer ear to the tympanic membrane). There are two sections:

1) There is a cartilaginous section of the EAM that contains hair follicles and ceruminous glands that produce cerumun (ear wax). These hairs and wax trap foreign particles from entering the middle ear and protect the tympanic membrane.
2) There is a bony section of the EAM that is lined with delicate skin that does not have hair follicles or ceruminous glands.

Question 12

What is the tympanic membrane covered with?

Answer 12

Skin externally and mucous membrane internally.

Question 13

What is the umbo?

Answer 13

The tympanic membrane has a shallow depression called the jumbo. It serves as an attachment point for one of the ossicles of the middle ear - the malleus.

Question 14

Where is the malleus attached to?

Answer 14

The inner surface f the tympanic membrane at the umbo.

Question 15

Name the 3 ossicles of the middle ear and their functions?

Answer 15

1) the malleus
2) The incus
3) the stapes

Question 16

Describe the location and boundaries of the middle ear?

Answer 16

The middle ear begins at the tympanic membrane. Located internal and superior to the tympanic membrane in the temporal bone.
BOUNDARIES: laterally by the tympanic membrane and medially, by a bony wall with two windows (i.e separates the middle from the inner ear).
It is divided into to sections by the ossicles. There are two air filled cavities:
1) the epitympanic recess
2) the tympanic cavity

Question 17

What is the paryngotympanic tube and what is its function?

Answer 17

It is a canal between the middle ear and the nasopharynx. It allows air pressure in the middle ear to be equalised by allowing air to leave and enter the tympanic cavity.
this is important = allows free movement of the tympanic membrane.

Question 18

What 3 muscles contribute to the opening of the pharyngotympanic tube/auditory tube/eustachian tube?

Answer 18

1) The tensor levi palatini
2) the levator levi palatini
3) salpingopharyngeus muscle

(as these are muscles of the palate and pharynx -swallowing or yawning can often help equalise air pressure)

Question 19

What structures make up the middle ear?

Answer 19

1) the ossicles (malleus, incus and stapes)
2) stapedius and tensor tympani muscles
3) chords tympani nerve (branch of the facial nerve)
4) tympanic plexus of nerves

Question 20

Name the bones of the middle ear and their attachment points. Also, what is their function?

Answer 20

1) The malleus
2) The incus
3) the stapes

They are the 3 smallest bones in the body and take up most of the structure of the middle ear. They stretch from the inner medial surface of the tympanic membrane (the malleus via the umbo) to the oval window (the stapes footplate occupies the oval window).
Their functions are:

1) to transmit sound vibrations to the fluid of the inner ear.
2) help limit damage to the inner ear by tensing when there is excessively strong vibrations

Question 21

How many times greater is the vibratory force of the stapes compared to the tympanic membrane and why?

Answer 21

10 x greater. Its base is smaller and more force is required to vibrate fluid than it is air.

Question 22

What are the two muscles that dampen the movements of the ossicles?

Answer 22

The tensor tympani and the stapedius muscle.

Question 23

Describe the function of the tensor tympani muscle?

Answer 23

It is attached to the malleus ossicle of the middle ear. When it contracts it pulls the malleus anteromedially causing the tympanic membrane to become taught.
It is innervated by CNV3 (the mandibular branch of the trigeminal nerve).

Question 24

Describe the function of the stapedius muscle.

Answer 24

It is attached to the stapes and the interior wall of the middle ear. when it contracts it rotates the stapes posteriorly.
Innervated by facial nerve (VII).

Question 25

What is the combined function of the stapedius and the tensor tympani muscles?

Answer 25

They protect the inner ear.
Together these muscles function to stiffen the middle ear transmission system. They provide intensity control by reducing transmission of acoustic information in LOWER FREQUENCIES = reduces the strength of signal reaching inner ear thus protecting it from damage.
This stiffening does not reduce the frequency of higher pitched sounds.

Question 26

What is sound attenuation reflex?

Answer 26

Together the stapedius and tensor tympani function to stiffen the middle ear transmission system. As such they provide intensity control by reducing the transmission of acoustic information in the lower frequencies. This reduces the strength of the signal reaching the inner ear and thus protects it from damage. This is called the sound attenuation reflex.

Question 27

Where is the inner ear located?

Answer 27

It is located in the petrous part of the temporal bone.

Question 28

Describe the anatomy of the inner ear?

Answer 28

THE BONY LABYRINTH
There is a bony (osseous) labyrinth within the inner ear. It is essentially a series of tunnels and chambers within the temporal bone. They are filled with perilymph fluid. The bony labyrinth consists of 3 parts: 1) the vestibule 2) the semicircular canals 3) cochlea

THE MEMBRANOUS LABYRINTH
The membranous labyrinth is inside the bony labyrinth suspended in perilymph fluid.Inside the membranous labyrinth is endolymph fluid.

Question 29

What is the vestibule in relation to inner ear?

Answer 29

The vestibule is the entrance to the inner ear. It is located between the cochlear and the semicircular canals.
FUNCTION: is to maintain balance.
The lateral wall of the vestibule features the oval window.

Question 30

What are the semicircular canals in relation to the ear?

Answer 30

There are 3:

1) Anterior
2) posterior
3) lateral.

they exist on 3 planes so we can feel the position of the head in 3 planes (nodding, rotating and tilting head). Sagittal, horizontal and coronal).
Each semicircular canal opens on to the vestibule.

Question 31

What is the cochlear in relation to the ear?

Answer 31

The cochlear is the final part of the osseous labyrinth (bony).
The cochlea curls 2 3/4 times before reaching the APEX of the cochlea.
The modiolus is the core of the cochlea made of perforated bone.

Question 32

Summarise how sounds travels/sound waves reach the inner ear?

Answer 32

1) captured by auricle and travel via the ext auditory meatus to the tympanic membrane
2) the tympanic membrane vibrates
3) This in turn causes the vibrations of the malleus, incus and stapes
4) As the stapes is connected to the oval window (which connects the middle and inner ear) the vibration of the bones vibrate the fluid to vibrate in inner ear (via oval window)
5)This vibration causes changes in shape of the basilar membrane
6) Hair cellsin the basal membrane send action potentials
in response to shape changes
7) The nerve impulses are carried via the vestobulocochlear nerve to the primary auditory area in the temporal lobe.

Question 33

What type of fluid does the bony labyrinth contain in the inner ear?

Answer 33

Perilymph

Question 34

What kind of fluid does the membranous labyrinth contain in the inner ear.

Answer 34

Endolymph

Question 35

What is the inner ear comprised of?

Answer 35

It is comprised of a bony labyrinth of hollow cavities and air spaces. Within these are a fluid called perilymph and a membrane called the membranous labyrinth. Within the membranous labyrinth there is a fluid called endolymph fluid. Both of these fluids are important for carrying sound waves to organs of hearing and balance.

Question 36

What is the modiolis?

Answer 36

The core of the cochlea

Question 37

What is the scala media

Answer 37

cochlea duct and it houses the organ of hearing.

Question 38

What are the two chambers of the inner ear?

Answer 38

the scala tympani and the scala vestibuli.

Question 39

What are the two chambers of the inner ear filled with?

Answer 39

the scala tympani and the scale vestibuli are filled with perilymph liquid.

Question 40

What is the difference between static and dynamic balance.

Answer 40

The inner ear has two systems for regulating balance: a static system and a dynamic system.
The static system consists of the utricle and saccule. This system evaluates the position of the head relative to gravity and also linear acceleration or deceleration.
Dynamic balance is regulated by the semicircular canals. The three semicircular canals are at right angles to each other: this allows us to detect movement in all directions.