Flashcards in H&N 7.1 The ear. Deck (69):
What are the functions of the ear?
(-equilibrium of pressure)
How can the ear be divided up into parts?
What makes up the outer ear?
-external aurditory meatus
-lateral surface of tympanic membrane
What's another name for the auricle?
What are some common signs/symptoms of pathology of the ear?
loss of hearing
in what bone is the ear?
The petrous part of the temporal bone
What are the anatomical parts of the pinna?
What is the pinna made up of?
Cartilage, fatty tissue and skin.
What is the function of the auricle?
To 'catch' sound and direct it within the ear, and to the tympanic membrane.
What abnormalities can occur in the pinna of the ear?
-facial nerve palsy (leads to vesicles and inflammation)
What is a pinna haematoma?
What causes it?
Due to blunt trauma, there is a build up of blood between the cartilage and overlying perichondrium. This looks like a big bulging ear.
What are the risks of the pinna haematoma?
The cartilage normally recieves its nutrients from the perichondrium, so when this is stripped away by the collection of blood, the cartialge can undergo necrosis (pressure necrosis due to the pressure exerted by the blood).
This can lead to a cauliflower ear.
Why does a cauliflower ear develop?
Pinna haematoma has lead to necrosis of the cartilage of the ear.
New cartilage is laid down but in an uncoordinated fashion, which along with fibrosis leads to an asymetrical, funky looking ear.
How would you treat a pinna haematoma?
promtly draining the blood and ensuring there is no reaccumulation and the cartilage and perichondrium are reapposed.
Give some features of the external accoustic meatus?
-it's a skin lined cul-de-sac.
-it contains hairs and wax
-it is around 2.5 cm long
-it is sigmoid in shape
What is the structure of the external auditory meatus?
outer 1/3 made from cartilage.
inner 2/3 made from bone.
How does the ear clean itself?
dead skin cells and other debris get deposited within the external ear canal.
This collects and forms wax.
The hairs move this wax out of the ear.
What is the process of shedding skin/the outer layer of cells known as?
What is the function of wax?
it helps to prevent objects from enterring deeper into the canal.
What are some common conditions affecting the external accoustic meatus?
-accumulation of wax (can lead to conductive hearing loss)
What is otitis externa?
What is a common cause?
infection of the external accoustic meatus.
Causes inflammation, some discharge
How would you treat otitis externa?
Antibiotic/steroid drops for the ear.
What should you be able to see when looking into the ear on the tympanic membrane?
-handle of malleus and umbo
-long process of incus
-parsa tensa (tightly stretched membrane)
-parsa flacid (looser membrane)
-cone of light
What abnormalities might you see of the tympanic membrane?
-perforation (eg due to cotton bud)
-bulging and loss of features (otitis media)
-straw coloured fluid behind (glue ear)
-may be pulled inwards (negative pressure of middle ear, due to dysfunction of eustachian tube)
-may see grommits.
What are the main anatomical components of the middle ear?
-tensor tympani muscle
What anatomical relations does the middle ear have?
-facial nerve (and chorda tympani runs through tympanic cavity)
-mastoid air cells
-internal jugular vein (inferiorly)
-internal carotid artery (anteriorly)
What are the 3 osccicles?
What's the function of the ossicles?
The malleous is attached to the tympanic membrane, and the others forma chain, attaching the inner ear.
They vibrate when the tympanic membrane does, and amplify the vibration, so we can hear sound.
What muscles are present in the ear?
What are their innervations?
What is their function?
-stapedius (facial nerve)
-tensor tympani (mandibular nerve, Vagus)
They contract in response to loud noise, to dampen the sound and protect the hearing apparatus.
Known as the acoustic reflex.
What symptom do you get if the innervation to the stapedius/tensor tympani gets interrupted?
Where is the epitympanic recess adn what is it's relevance?
Found abouve the ympanic cavity and in close proximity to the mastoid air cells will lie posteriorly.
There is communication between the mastoid cells adn the epitympanic recess via the mastoid antrum.
Pathology of the middle ear can invovle the mastoid air cells and cause mastoiditis.
What is the function of the mastoid air cells?
They act as a resivoir of air, and release air into the cavity when there is negative pressure in the middle ear.
What is mastioditis?
How do you treat?
Infection of the mastoid air cells.
Becuase they are porous they are ideal for pathogenic replication.
Pus needs to be drained from the air cells (avoiding facial nerve) and antibiotics will need to be given.
What are the serious complications that can occur due to mastoiditis?
Meningitis through spread to the middle cranial fossa.
What is the auditory tube also known as?
Where does the auditory tube go from and to?
From the anterior middle ear, to the inferior concha in the nasal cavity.
What is the function of the auditory tube?
To equilibriate pressure between the middle air and the atmosphere.
What is glue ear?
Otitis media with effusion.
It is NOT an infection (but can lead to otitis media, god breeding ground)
Due to dysfunction of the auditory tube, leading to negative pressure within the middle ear.
This draws air out of the cells and leads to the straw like transudate accumulating in the middle ear.
The tympanic membrane will be drawn inwards.
can affect hearing due to the transudate formed,
What is otitis media and what are the associated features?
middle ear infection, due to eustachain tube defects.
You get bulging of the tympanic membrane and loss of features. (if excessive this can lead to tympanic membrane perforation).
Will present with otaligia, fever, hearing loss.
What is the result of glue ear?
May resolve on it's own wihtin a few month.
Predisposes to infection so could cause otitis media.
May need grommets to resolve.
Why are children more likely to get otitis media than adults?
Their eustachian tube is shorter and more horizontal, so bacteria from the nasal cavity is more likely to ascend/ the tube can get blocked more easily (which predisposes to infection.
What are some complications of otitis media?
-tympanic membrane perforation.
-facial nerve involvement (runs close to tympanic cavity, through the petrous bone)
-intracranial complications involving raised ICP, meningitis, sigmoid sinus thrombosis or a brain abscess.
How would you recognise mastoiditis?
Ear may be pushed forwards, mastoid process may be red/swollen/painful
Pain (child may tug at ear).
What is cholestaemia?
A benign growth of skin cells which develops secondary to chronic/recurring ear infections.
Why does cholesteatoma form?
Chronic infections/disorders of the eustachian tube leads to a negative pressure in the middle ear.
This leads to a small pocket forming near the top of the tympanic membrane, where skin cells and debris can accumulate.
What is a complication of cholestaetoma?
The benign growth can errode structures.
It begins with the osssicles (which will result in hearing loss) and may continue into the surrounding bone and even the brain.
What is the treatment for a cholesteatoma?
-surgical removal (not urgent but needs doing)
done via a mastoidectomy to remove affect mastoid air cells, and a tympanoplasty to repair the damaged tympanic membrane.
What are the main components of the inner ear and their functions?
-cochlea (for hearing)
-vestibular apparatus (for balance and sense of position)
What are the components of the cochlea?
-cochlea branch of CN VIII.
-fluid within the cochlea.
How does the cochlea allow us to hear?
The movement of the ossicles is transmitted through the oval window.
This cuases movement of the cochlea fluid.
This stimulates special sensory cells within the cochlea duct with fire action potentials down the vestibulocochlea nerve to the brain.
What type of hearing loss is associated with the cochlea?
Sensorineuronal hearing loss.
What are the components of the vestibular apparatus?
-the semi lunar canals (membranous and bony labrynth)
How do the semilunar canals work?
They are in all 3 planes, and so any movement is detected, and feeds back to the brain lettins us know our position.
What is vertigo?
The feeling of you/the environment moving, when in fact it is not,
eg room spinning
What is tinnitus?
The hearing of sound when there is no external sound.
Eg ringing in ears, or whoosing.
What is Meniere's disease?
A long term condition affecting the inner ear, where there are attacks of vertigo, tinnitus, hearing loss etc, which last for a few hours at a time.
The exacct cause is unclear, but thought to be due to the pressure in the inner ear.
There is no cure but treatment to control the symptoms are used.
What is BPPV?
Benign paroxismal positional vertigo.
Occurs when crystals within the ear get dislodged (eg due to trauma) and float around the semi lunar canals.
Leads to dizziness and nausea when in certain positions such as lying down or looking up.
What is the treatment for BPPV?
Often will resolve on it's own after a few weeks,
If not, you can move the head through a series of movements to move the crystals back into place. (this depends on where the crystal is in the semi lunar canals)
What is Ramsy Hunt syndrome?
When shingles affects the facial nerve within one of the ears.
Causes the painful shingles rash but can also cause facial palsy on the affected side as well as hearing loss.
Treatment involves antivirals, steroids to reduce inflammation and pain relief.
The quicker it gets treated, the less damage will be done.
What tests are done to test hearing?
Rinne and Weber tests.
Describe the Rinne test, and what the findings indicate.
Use a tuning fork and see if the patient can hear it through the air, then place it on the mastoid process and see if they can hear it (louder or quieter).
If AC>BC this is normal or may indicate a sensorineuronal loss.
If BC>AC this suggests a conductive hearing loss in that ear.
Describe how to conduct the Weber test.
Place the tuning fork firmly in the centre of the forehead, and ask the patient if they can hear the sound equally, or if it localises.
Describe the results of the Weber test.
If the sound is symetrical, this suggests normal hearing, or bilateral equal conductive/sensorineural hearing loss.
If the sound loacalises to the ear with normal hearing (AC>BC) this suggests a sensorineural loss in that ear.
If the sound localises to the ear with the worse hearing (BC>AC) This is suggestive of a conductive loss of that ear.
What do the following results indicate?
Weber- lateralised to the right
Rinne- negative on the right.
Right conductive hearing loss.
What do the following results indicate?
Weber-lateralised to the right
Rinne- positive bilaterally
left sensorineural hearing loss.
what do the following results indicate?
Weber- no lateralisation
Rinner- positive bilaterally
Normal hearing (No hearing loss)
Bilaterally equal sensorineural hearing loss.
What do the following results indicate?
Weber- no lateralisation
Rinne- negative bilaterally
Bilaterally equal conductive hearing loss.
What instrument do you use to test hearing?
512 Hz tuning fork