The Ear

Question 1

What bony part of the head are the ear cavities housed in?

Answer 1

The pterous part of the temporal bone

Question 2

What are some of the features of the auricle?

Answer 2

External lateral paired structure, that captures and transmits sound to the external acoustic meatus, and mostly a cartilgnous framework wiht the lobule being the only part not supported by cartilage

Question 3

How can a facial nerve palsy present in the ear?

Answer 3

Ramsay hunt is an acute peripheral facial neruopathy, associate with an erymateous vescicular rash of the skin of the auriclae and the ear cannal.

Question 4

How can you develop a pinna heamotoma?

Answer 4

Secondary to a blunt injury to the pinna that is common in contact sports, there is an acculumation of blood between the cartilage and perichondrium, which deprives the cartilage of its blood supply and causes pressure necrosis of tissue

Question 5

How would you treat a pinna heamotoma?

Answer 5

Reapposition of the two layers are necessary, and this can help to restart the blood supply.

Question 6

What would happen if a pinna heamotoma was to be left untreatd?

Answer 6

Would lead to fibrosis and the formation of new asymetrical cartilage, and causes the development of a cauliflower ear or a boxers ear

Question 7

What are some of the key features of the internal acoustic meatus?

Answer 7

Is a skin lined cul de sac, and is a sigmoid shape, the outer 1/3 is cartilagnous whereas the inner 2/3 is non cartilagnous, and is has hairs and some wax production

Question 8

What is the function of the hairs and wax of the ear?

Answer 8

Prevents objects from entering the ear canal, adn also aid in desqauamation and skin migration out of the canal

Question 9

How long is the external acoustic meatus?

Answer 9

2.5 cm

Question 10

What is ottis externa?

Answer 10

Inflammation of the external acoustic meatus, and this often occurs in swimmers or may be the result of a bacterial infection, itching and pain in the external ear and pulling the auricle or putting pressure on the tragus increases the pain

Question 11

What is the part of the tympanic membrane that will vibrate the most?

Answer 11

The pars tensa

Question 12

What is the function of the tympanic membrane?

Answer 12

Moves in response to the air vibrations and helps these movements go towards the ossicles

Question 13

What are some of the causes of perforation of the tympanic membrane?

Answer 13

Often caused by trauma and infection, and may result from ottis media, and can result from foregin bodies in the external acoustic meatus

Question 14

What are the three ossciles called?

Answer 14

The malleus, the incus and the stapes

Question 15

What type of joints are there between the ossicles?

Answer 15

Synovial joints

Question 16

How do the ossicles communicate sound to the inner ear cavity?

Answer 16

Base of the stapes joints the oval windows, and these help amplify the vibrations to the fluid wihtin the cohela.

Question 17

What are the mastoid air cells?

Answer 17

Air filled spaces in the mastoid proccess of the tempioarl bone, and these air cells are in the mastoid antrum, communicate with the middle ear, and act as a buffer to help equalise the pressures

Question 18

What is the role of the pharyngotympanic tube/

Answer 18

Allows equlibration of pressure between the middle ear cavity and the atmosphere, and is improtant in the ventiliation and drainage of mucus within the middle ear, walls are usually closed

Question 19

What is ottis media with effusion (glue ear)?

Answer 19

Is not actually an infection, there is persistant dysfunction of the auditory tube, and this is unable to equalise middle ear pressure, and therefore a negative pressure develops in the middle ear, and this leads to a build up of fluid, and the ear drum becomes innverted with fluid visible within the innner ear, and this decreases the mobility of the tympanic membrane and therefore decreases hearing

Question 20

What is ottis media?

Answer 20

An acute middle ear infection, more common in children, and otalgia and other non specific symptoms such as a temperature, and there is a red and bulding tympanic membrane, and is often secondary to upper respinfection

Question 21

What could happen if ottis media is left untreated?

Answer 21

May produced impaired hearing through scarring of the auditory ossicles

Question 22

Why are middle ear infections more common in children?

Answer 22

The pharyngotympanic tube is shorter and more horziontal in infants, and therefore there is easier passage of infection from the nasopharynx to the middle ear

Question 23

What are some of the possible complications of ottis media>?

Answer 23

Tympanic membrane perforation, facial nerve involvement as this runs through the pterous part of the temporal bone, and also rarer but mastoiditis, mennigiti, sigmoid sinus thrombosis and brain abcesses

Question 24

What are the important antatomical realtions of the ear?

Answer 24

Pharyngotympani, sigmoid sinus and the mastoid cells

Question 25

What are some of the features of mastoiditis?

Answer 25

If mastoid proccess is infected it can spread to the middle craial fossa and then into the brain cause mennigits (can spread through the pterosquamous fissure in children)

Question 26

What is the relationship between the facial nerve and the middle ear cavity?

Answer 26

The facial nerve, in paticulary the chorda tympani branch, goes through the posterior wall of the middle ear cavity and therefore the facial nerve may be involved in the pathology of the middle ear

Question 27

What is a cholesteotoma?

Answer 27

A rare, destructing and expanging growht of kertainising sqaumous epithelium in the middle ear and the mastoid proccess, and this usuially occurs secondary to chronic and recurring ear infections

Question 28

How does a cholesteotoma form?

Answer 28

There is sucking negative pressure, pulling the ear drum inwards and can lead to a small pocket forming, where skin cells get trapped and continue to grow, is not malignat but slowly grows and expands

Question 29

What happens as a cholestoma forms?

Answer 29

Is more likley to grow into, erode and destroy structures of the middle ear,

Question 30

What are some of the features of the cochlea?

Answer 30

Is our organ of hearing, and is a fluid filled tube, and movements at the oval window set up movements of the fluid wihin the cohlea, hearing loss involving the cochlea is sensorinueal hearing loss

Question 31

How does hearing occur at the cochlea?

Answer 31

Vibration of ossicles and the stapes at the oval window sets up the vibrations and the movements in the cochlear fluid, and this is sensed by the nerve cells in the cochlear duct, and movement of these recetpros in organ of corti trigger action pontentials at CNVIII

Question 32

What are some of the features of the vestibular appartus?

Answer 32

Located in the semicircular canals, these are structures that respond to positon and rotation and help to maintain out balance,

Question 33

How do the semicircular canals work to maintain balance?

Answer 33

Upon movement of the head the flow of endolymph changes speed or direction, and sensory receptors detect this change, and send signals to the bone

Question 34

What is menieres disease?

Answer 34

Is a disorder of the inner ear characterised by episodes of vertigo and low pitched tinntus and hearing loss, and these are thought to be caused by excess aculmations of endolymph wihtin a membranous lanbyrith, causing distention of the ducts

Question 35

When is benign paraxysmal postional vertigo?

Answer 35

Repeated, brief periods of vertigo with movement, a spinning sensation on changes of position, a small calcified olith is disloged from its usual psotion, and has migrated to the smemicriular canals, causing abnormal fluid displacement and thus the sensation of vertigo