Ear Flashcards
How many parts is the ear split into and what are they?
3
External, middle and inner
What is the medical term for ear pain?
Otalgia
What are the 2 types of hearing loss?
Conductive
Sensorineural
The ear is within which bone?
Petrous part of the temporal bone
The external ear runs from … to…
Pinna/auricle to the tympanic membrane
What is the role of the external ear?
Collect, transmit and focus sound waves onto the tympanic membrane
What do we call the fold at the very top of the outer ear?
Helix
What do we call the dangly bottom part of the external ear?
Lobule
Describe the composition of the pinna
Elastic cartilage with skin closely adhered to it
When do you get Boxer’s/Cauliflower ear?
After repeated trauma to the ear
What is Ramsay-Hunt syndrome?
Infection
Shingles of the facial nerve
Causes vesicles is ear and facial nerve palsy
What is a pinna haematoma and why is it dangerous?
Secondary to blunt injury to pinna
Accumulation of blood between cartilage and perichondrium
Perichondrium supplies blood to cartilage therefore this can lead to loss of blood supply and/or pressure necrosis of the cartilage
What Mx do we need for pinna haematoma?
Prompt drainage
Measures to prevent reaccumulation
Reapposition of the 2 layers
Describe the structure of the external acoustic meatus
Skin lined curl-de-sac keratinised Sigmoid shape Cartilaginous outer 1/3 Bony inner 2/3
How do we straighten the ear to look inside?
Pull the ear up and back
How does the EAM self clean?
Ear wax
Migration to outer part
What is the length of the EAM?
2.5 cm
What is otitis externa?
Very common
Infection and inflammation - ear canal swells, very painful
‘Swimmer’s ear’
Can be hard to tolerate the ear examination
Treat with ear drops: Abx or steroid
Describe the tympanic membrane
Pearly, translucent, tightly stretched, fibrous CT
What features can be seen looking at the tympanic membrane?
Long process of incus Handle of malleus (middle) Pars flaccida (loose tissue above malleus) Pars Tessa Cone of light
What compromises the middle ear?
Ossicles
Air filled cavity - tympanic cavity
What is the role of the ossicles?
Amplify vibration from membrane to cochlea via the oval window
What is the order that vibrations travel through the ossicles?
Malleus > incus > stapes
What is the Eustachian tube?
Allows equilibration of pressure in middle ear with the atmosphere
Ventilation and drainage of mucus
Middle ear to nasopharynx
Describe otitis media with effusion
(Glue ear)
Not an actual infection
Build up of fluid and negative pressure in middle ear
Eustachian tube dysfunction
Decreased mobility of membrane and ossicles - affects hearing
Most resolve spontaneously - some need grommets
Describe otitis media
Acute middle ear infection More common in infants/children Otalgia Temperature Red +/- bulging T membrane and loss of features of TM
Why are middle ear infections more common in children?
Eustachian tube is shorter and more horizontal
What are some complications of otitis media?
TM perforation
Facial nerve palsy
Rare = mastoiditis, meningitis
What are mastoid cells?
Air cells of bone that communicate with the middle ear
Describe mastoiditis
Red and swollen behind ear
Ear pushed forward
Refer straight to hospital
Which part of the facial nerve runs through the middle ear and what does it supply?
Chorda tympani branch
Supplies taste to anterior 2/3 tongue
What is a cholesteatoma?
Skin cells get trapped and grow - small pocket forms at top of middle ear
Not malignant but slowly erodes into structures eg. Ossicles
Usually secondary to recurring/chronic ear infections
What makes up the inner ear?
Vestibular apparatus and cochlea
What is the role of the vestibular apparatus?
Sense of position and balance
What is the role of the cochlea?
Converts sound vibrations into electrical signals
How many semicircular canals do we have?
3
Where are the special sensory cells of the ear?
In the cochlear duct
Where is the problem with sensorineural hearing loss?
Cochlear or nerve supplying it
Where is the problem in conductive hearing loss?
External or middle ear
Describe how sound moves from vibrations to the brain
Vibration of ossicles
Movement of cochlear fluid
Sensed by nerve cells of cochlear duct in spiral organ of Corti
Trigger APs in the vestibulocochlear nerve (VIII)
To the brain
Why do we have 3 semicircular canals?
Arranged in different planes
Sense different movements
Give some problems with the vestibular apparatus
Vertigo
Ménière’s disease
Benign paroxysmal positional vertigo
