Anatomy and Diseases of the Ear Flashcards
What makes up the external ear?
Auricle
External auditory canal
What are the parts of the auricle/pinna?
Helix Antihelix Triangle fossa Crus of helix Concha Tragus External auditory meatus Antitragus Lobule
Tips for examining the pinna
Always examine the ear from front, sides, behind and inside
Never forget to compare both sides
What is a pinna haematoma?
It is a haematoma between cartilage and perichondrium preventing oxygenation resulting in pressure necrosis
Also known as cauliflower ear
What are the parts of the middle ear?
Tympanic membrane (at a 45 degree angle) Ossicles/bones Muscles Eustachian tube Mastoid air cells
What are the parts of the tympanic membrane?
Pars flacida Lateral process of malleus Handle of malleus Umbo Pars tensa Light reflex (points towards the feet)
How do you perform a tympanic examination?`
Gently pull pinna outwards backwards and upwards
Gently insert otoscope
and always examine the whole eardrum
What are the bones of the middle ear?
Malleus (hammer)
Incus (anvil)
Stapes (stirrup)
What is special about the bones of the middle ear?
They are the smallest bones in your body
What are the muscles of the middle ear and what is their purpose?
Tensor tympani
Stapedius
Their function is to protect against loud noises
How is a child’s eustachian tube different to an adult’s?
And what is the clinical relevance of this?
A child’s is wider and more horizontal
It is easier for an infection to spread to the ear.
What is tympanic retraction?
When there is negative ear pressure it leads to retraction of the ear drum
This happens in eustachian dysfunction
What is acute otitis media?
An acute infection of the middle ear cavity
The negative middle ear pressure leads to retraction of the ear drum
When you have chronic otitis media with effusion you get glue ear
Thick effusions accumulate behind the ear drum
Secondary to prolonged negative pressure
Results in conductive hearing loss
Can use a grommet to treat, puts a tube for fluid into the ear drum.
What are the complications of acute otitis media?
Chronic Perforation CN VII Palsy Labrinthitis SNHL Mastoiditis Meningitis Cerebral abscess
What is cholesteatoma?
Negative middle ear pressure >
Keratin balls sticks to retraction pockets>
Necrotic mass of dead cells (cholesteatoma)>
Erosion of middle ear & bone from lytic enzymes created by the dead cells
How can CN VII dysfunction be caused by an ear infection?
The CN VII runs through the middle ear and is vulnerable to damage from the middle ear disease
The chorda tympani can also be affected
What is in the inner ear?
Cochlear component
Vestibular component
What is the function of the cochlear component?
Hearing
What is the function of the vestibular component?
And very briefly how does it do this? (structure)
Balance
Made of three semicircular canals filled with fluid (Superior, Posterior, Lateral/horizontal)
2 Sacs of fluid - Utricle and Saccule
Balance is achieved by a huge coordination between many parts of the body
The organ is hugely sensitive
One sac can tell if you move up or down
One can tell if you move forward or backwards
And the semicircular canal does the rest
Basically the fluid moves within these sacs and moves jelly surfaces with finger like projections and that translates to balance and perception of movement
What is BPPV?
Benign Positional Paroxysmal Vertigo
Typically last seconds
Especially turning head
It is due to otolith displacement, the crystals move forward and keep moving when you stop.
Feel like you are still moving when you aren’t
What is Meniere’s disease?
Classic 4 symptoms:
- Vertigo
- Hearing loss
- Tinnitus
- Aural fullness (Can present variable)
Due to endolymphatic hydrops
Too much fluid in vestibules
How does the cochlear work? (Very simple)
It is like a sausage with three layers filled with fluid.
The stapes connects to the top layer, it moves then moves the top layer which then moves the middle layer which has sensory cells and send the signal to the brain and then the excess vibrations travel into the bottom layer to protect the middle layer.
The top layer connects to the bottom and this means that loud noises can vibrate all around and be put back out as to not damage the ear.
