Session 6 - Ear anatomy

Question 1

What are the three main parts of the ear?

Answer 1

The external, middle and internal ear.

Question 2

What is the main, visible part of the external ear?

Answer 2

The auricle

Question 3

What are the three main features of the external ear?

Answer 3

The helix
The tragus
The lobule

Question 4

What is the blood supply to the external ear?

Answer 4

The posterior aurcular and superficial temporal arteries, which are both branches of the external carotid artery

Question 5

What is the sensory innervation anterior to the external acoustic meatus?

Answer 5

Auriculotemporal nerve, a branch of the mandibular nerve

Question 6

What is the sensory innervation of auricle behind the EAM

Answer 6

Great auricular nerve

Question 7

Outline the structure of the EAM canal

Answer 7

Cartaliginous tube for the lateral 1/3rd, bony canal for the medial 2/3rds

Question 8

Where does EAM lie?

Answer 8

In the temporal bone

Question 9

What is the gooey stuff in ears?

Answer 9

Cerumen, which mixes with dead skin cells to form wax

Question 10

What is the best way to view the EAM in adults?

Answer 10

Pull the ear upwards and backwards

Question 11

What is the best way to view the EAM in children?

Answer 11

Auricle is pulled downwards and backwards

Question 12

What can be visualised through the tympanic membrane?

Answer 12

The malleus

Question 13

What is the external surface of the tympanic membrane innervated by?

Answer 13

Auriculotemporal nerve branch of CN V3

Auricular branch of the vagus nerve CN X

Question 14

What is the internal surface of the tympanic membrane supplies by?

Answer 14

The glossopharyngeal nerve

Question 15

What is Arnold’s cough reflex?

Answer 15

Stimulation of the auricular branch of the vagus nerve, by touching the tympanic membrane with a cotton bud, can cause cough/vomiting

Question 16

What is wrong with the tympanic membrane if you can see dense white plaques?

Answer 16

Tympanosclerosis

Question 17

What does bulging of the tympanic membrane mean?

Answer 17

Pus or fluid in middle ear (otitis media)

Question 18

What would a retracted tympanic membrane demonstrate?

Answer 18

Infratympanic cavity pressures reduced due to obstruction of eustachian tube

Question 19

What is found in the middle ear?

Answer 19

Auditory ossicles 
- Malleus 
- Incus
- Stapes
Stapedius and tensor tympani msucles
Chorda tympani nerve 
Tympanic plexus of nerves

Question 20

What are the two parts of the cavity of the middle ear?

Answer 20

Tympanic cavity proper

Epitympanic recess

Question 21

What is found in the tympanic cavity proper?

Answer 21

Connected anteromedially with the nasopharynx by the eustachian tube
Connected posterolaterally with the mastoid air cells through the mastoid antrum

Question 22

What is the tympanic cavity lined by and what is it continius with?

Answer 22

Mucous membrane, continous with lining of the pharyngotympanic tube, mastoid air cells and mastorid antrum

Question 23

When is the mastoid antrum open?

Answer 23

During swallowing, thanks to the action of the palate muscles

Question 24

What is the porpoise of the ossicles?

Answer 24

Relay the vibrations encountered by the tympanic membrane to the internal ear, amplifying and concentrating sound energy to the oval window

Question 25

What are the two parts of the malleus?

Answer 25

Handle is attached to the tympanic membrane | Body articulates with the body of the incus

Question 26

What does the incus articulate with?

Answer 26

The stapes

Question 27

What does the stapes articulate with?

Answer 27

THE BONY LABYRINTH OF THE INNER EAR AT THE OVAL WINDOW No need to shout :(

Question 28

Outline the location and role of the tensor tympani

Answer 28

o Inserts into the handle of the malleus  Pulls handle medially  Tenses the tympanic membrane, reducing the amplitude of its oscillations o Prevents damage to the inner ear when exposed to loud sounds

Question 29

Outline the location and role of the stapedius

Answer 29

o Pulls the stapes posteriorly and tilts its base in the oval window  Tightens the anular ligament and reduces the oscillatory range o Prevents excessive movement of the stapes o Nerve to Stapedius arises from the Facial Nerve (CN VII)

Question 30

What is the most important anatomical relationhsip of the middle ear?

Answer 30

The facial nerve, which lies in the facial canal separated from the tympanic cavity by a very thin bony partition

Question 31

Where is the inner ear found?

Answer 31

In the petrous temporal bone. This bone forms bony labyrinth, surrounding the membranous labyrinth

Question 32

What five structures does the inner ear contain?

Answer 32

``` Vestibule Semi-circular ducts and canals Choclea Cochlear duct Organ of corti ```

Question 33

What is the vestibule of the inner ear?

Answer 33

 Small bony chamber, containing the Utricle and Saccule, which are sensitive to rotational acceleration and the static pull of gravity

Question 34

What is the semi-circular ducts and canals?

Answer 34

 Communicate with the vestibule |  Contain receptors that respond to Rotational Acceleration in three different planes

Question 35

What is the cochlea?

Answer 35

 Shell shaped portion of the bony labyrinth containing the Cochlear Duct

Question 36

What is the cochlear duct?

Answer 36

 Accommodates the spiral Organ of Corti

Question 37

What is the organ of corti?

Answer 37

 Contains the receptors of the auditory apparatus