?
What are the names of the 3 bony ossicles?
1. Malleus (hammer)
2. Incus (anvil)
3. Stapes (stirrups)
Are the ossicles in the inner, middle, or outer ear?
Middle ear
Common name for inner, middle and outer ear infections?
Otitis interna, media and externa, respectively
Where is the eustachian tube located?
Connects middle ear to throat
What ion channels open when tip links of hair cells are stretched?
K+
Where do the ossicles span from/to and what is their function?
From tympanic membrane to oval window
Function: mechanically amplify and transmit sound vibrations from the air into the fluid-filled cochlea.
Which membrane runs along the cochlear duct, supporting the organ of corti?
Basilar
Why are young children more vulnerable to ear infections?
Eustachian tubes are shorter, narrower, and more horizontal = poorer drainage, easy bacteria path, swelling = quick blockage
What connects stereocilia in hair cells?
Tip links
True or false: each ear sends input to both sides of the brain
True
How does speed and magnitude of tympanic membrane movement impact sound?
Faster vibration = higher pitch sounds
Slower vibration = lower pitch sounds
Greater movement/magnitude = (interpreted as) loud sounds
What is the name of the 2 muscles that protect the ear?
Tensor tympani > reduces eardrum movement
Stapedius > limits ossicle vibration
Eustachian tube function (x2)
Equalises ear pressure
Drains fluid from middle ear to prevent infections
(Opens when swallowing/yawning)
Match the following:
Amplitude of waves
Frequency of waves
to
= pitch
= loudness
Amplitude = loudness
Frequency = pitch
Match the following contents to each duct:
Contents:
- perilymph
- endolymph
- perilymph
Ducts:
- Cochlear duct
- Vestibular duct
- Tympanic duct
Cochlear duct: endolymph
Vestibular duct: perilymph
Tympanic duct: perilymph
What does the attenuation reflex do?
Protects cochlear from loud sounds
List the 3 types of hearing loss and the location of damage for each
Conductive: no transmission through either external or middle ear
Central: Damage to neural pathway between ear and cerebral cortex or damage to cortex itself
Sensorineural: Damage to structures of inner ear
Which condition is known as 'swimmers ear' and what are the main structures affected?
Otitis externa
External auditory canal (cartilaginous + bony portions)
+/- tympanic membrane
Distinguish structures impacted in otitis media vs otitis interna
Otitis media:
Tympanic membrane
Middle ear cavity (becomes filled with fluid/pus)
Eustachian tube
Auditory ossicles
*can lead to mastoiditis*
Otitis interna:
Labyrinth + vestibular system/nerve
Clinical significance of Tympanic plexus
Otitis media: Swelling or purulent fluid in the middle ear irritates the sensitive tympanic plexus, leading to severe otalgia.
Name of the 3 x main ducts in the cochlear
1. Vestibular
2. Tympanic
3. Cochlear
"the cochlear nerve transmits action potentials from the primary auditory neurons to cochlear nuclei in the medulla, on their way to the auditory cortex"
Explain how the basilar membrane responds to sounds and how this translates to frequency.
Basilar membrane responds differently depending on frequency
Near the base: the membrane is stiff
Vibrations with high frequency/pitch sounds
As you move out distally: more flexible/ apex/distal end:
Responds to low frequency/pitch sounds
This tonotopic arrangement allows the cochlear to separate sounds by frequency
What structure in the pons/tegmentum aids with sound localisation?
Superior olivary nucleus
What are the 4 nerves in the middle ear and their approximate location?
Facial Nerve (CN VII): Traverses the medial and posterior walls of the middle ear inside the bony facial canal.
Glossopharyngeal Nerve (CN IX) / Tympanic Nerve (Jacobson’s Nerve): Enters the middle ear through the tympanic canaliculus and spreads across the promontory to form the tympanic plexus.
Trigeminal Nerve (CN V3 - Mandibular Division): Sends the tensor tympani nerve to innervate the tensor tympani muscle.
Sympathetic Fibers (Carotid Plexus): Postganglionic sympathetic fibers join the tympanic plexus on the promontory.