Wk 11 - The ear Flashcards
What are the 3 general components of the ear?
External ear Middle ear Inner ear
What makes up the external ear?
Auricle External acoustic meatus (so down to the tympanic membrane)
What epithelium lines the external acoustic meatus?
Skin Have hairs and cerumen glands
What are cerumen glands ?
The glands producing ear wax
What makes up the middle ear?
-tympanic cavity -3 ossicles -auditory tube -tympanic membrane
What is the middle ear filled with?
Air
What are the components of the internal ear?
- Cochlea
- Semicircular canals
What is the cochlea concerned with?
Hearing
What are the semilunar canals concerned with?
The position of head in space Also allows you to move your head while keeping eyes fixed on something
What are the 3 ossicles and what kind of joints are found between them?
-Stapes -Malleus -Incus Synovial joints
What is the most common cause of deafness?
Build-up of wax
What nerve supplies the inner ear?
Vestibulocochlear - supplies the vestibule and cochlea
What ossicle attaches to the tympanic membrane and where?
The handle of the malleus at the most concave part called the umbo
When does the auditory tube open up? (what action makes this happen?)
When you yawn
What condition can affect the synovial joints of the ossicles?
Arthritis - can make it harder to hear
Where does the stapes sit? What holds it in place?
the footplate sits in the oval window
Stapedius muscle
What two muscles are part of the reflex which protects the ear from loud noises?
Stapedius muscle
Tensor tympani
Describe the action of the stapedius muscle.
If there is a loud sound it is part of a reflex and it will contract and pull on the stapes to restrict its movement so it doesn’t move out and in too much
Describe the action of the tensor tympani.
It is attached to the handle of the malleus.
When there is a loud sound it contracts and pulls on the tympanic membrane to restrict movement/vibration and therefore sound
What nerve is the tensor tympani supplied by and it is formed from what pharyngeal arch?
CN5 - first pharyngeal arch
What nerve is the stapedius muscle supplied by and what pharngeal arch is it formed from?
CN7 - 2nd pharyngeal arch
Describe how sound is turned into an electrical impulse to be recieved in the brain.
When we hear sound, it causes the tympanic membrane to vibrate. This vibration causes the ossicles to vibrate also. The footplate of the stapes is in the oval window and when it vibrates the stapes is pushed into the middle ear which contains fluid. This fluid then compresses a little membrane and the movements create an electrical impulse which travels along the vestibulocohlear nerve to the brain for the sound to be interpreted.
What is infection of the external ear called? How is it treated?
Otitis externa
Flushing out the ear
What is infection of the middle ear called?
Otitis medial
Why are middle ear infections more common?
The infection can pass from the nasopharynx (e.g. throat infection) through the auditory tube to the middle ear
It can be difficult to clear some otitis media infection. What type of infectiosn are these?
Chronic otits media
Chronic otitis media can lead to what problem?
Breakdown of the tympanic membrane leading to pus in getting into the internal acoustic meatus
Patient won’t be able to hear as well as there will be pus around the ossicles
What is glue ear also termed?
Chronic otitis media with effusion
Describe what happens in chronic otitis media with effusion. How is it treated? What patients does it normally happen in?
Normally in kids
Tend to have a serious of sore thrats and the auditory tube becomes blocked due to swelling of the lymphatix tissues (tubal tonsils). Get a buildup of mucous in middle ear
Kid wont hear as well
Treatment is normally just mointoring the ear and it goes away on its own (if not put ventilation tube in)
Surgery to the ear (middle ear) can damage what nerve?
Facial nerve
A bad infection in the middle ear might interfere with what nerve?
Facial nerve
What ligament holds the stapes in place? What might happen to this ligament?
Angular ligament
Calcium deposition on the ligament which restricts the movement of the stapes and therefore is a cause of deafness
