Lecture 25 - Ear Flashcards
Where is the inner ear?
within the petrous part of the temporal bone
The outer ear is supported by …
cartilage - except for the lobule which has some fat in it
What carries the sound into the ear
external auditory meatus - through to the tympanic membrane
tragus is which part of the outer ear?
the bit that hair grows off, in front
The external auditory meatus is cartilaginous in which parts?.
lateral 1/3
medial 2/3 is embedded in the temporal bone
what releases wax in the ear?
cerumen glands - coats are prevents maceration of skin with water
what is sensory to the posteroinferior part of the outer ear?
vagus
what is sensory to the anterosuperior part and external surface of tympanic membrane?
Auroculotemporal nerve V3
good example of referred pain, can go to other branches of V3 - e.g to the tongue, inferior teeth
tympanic membrane has __ junctions all around it
tight jnctions - no holes, no mechanical energy lost
What is the cone of light?
antero-inferior quadrant - reflection is created if normal
if not normal the reflection will be somewhere else to to change in curvature
Where is the tympanic cavity proper?
directly medial to the membrane
Epitympanic recess is where? what does it communicate with?
superior to the cavity proper
communicates with sinuses in the mastoid
where does the auditory tube (pharyngotympanic tube) open in the middle ear
antero-inferior wall - project antero-medially towards to nasopharynx
auditory tube is largely..
cartilagenous
auditory tube allows equalisation of ..
pressure, only opening to the atmostphere for the middle ear
The ossicles from lateral to medial are
malleus
incus
stapes
The gradient of the auditory tube is higher in ____
adults - less likely to cause infection compared to kids
Tensor tympani hangs off the ____wall
what CN innervates it
anterior - attach to malleus
CN5 - trigeminal
T for tensor, T for trigeminal
Stapedius hangs off the ____ wall
what CN innervates it
posterior wall
CN7
what is the function of Stapedius and Tensor tympani
dampen really loud sounds
Chorda tympani is a branch of the ___ nerve, what does it supply
taste to ant. 2/3 of tongue
runs through middle ear
goes with lingual nerve towards the tongue
very complicated course
What is the promontary?
formed by the basal (first) turn of the cochlea
good marker for the two opening to the inner ear: Oval and round window
oval window is where energy comes __ to the inner ear
in
The internal carotid artery is very close to the
middle ear - can feel pulsations
The bony labyrinth is..
the space inside the petrous part of the temporal bone, filled with perilymph
The membranous labyrinth..
is one continuous sac which sits suspended in the bony labyrinth itself (within the perilymph).
has its own fluid inside - the endolymph
Round window acts a means to allow energy to escape the…
bony labyrinth - energy is transmitted by the mebrane back into the middle ear
There are semicirclar canals in the bony labyrinth which provide us with…
information regarding dynamic equilibrium
anterior
horizontal
posterior
What is between the cochlea and the semicirclar canals?
the vestibule
What are the receptors of the vestibule associated with..
static equilibrium
The membranous labyrinth is a ___ __ filled with endolymph
The membranous labyrinth is a closed sac filled with endolymph
The ampulla (swellings) at the base of the semiciruclar dcts are responseible for..
dynamic equilibrium - head movements
What are the to swellings of the vestibule?
utricle and saccule
The vestibular nerve and cochlear nerve come together to form..
CN8
the cochlea, if you were to unroll it, projects…
antero-medially
frequencies deflect different hair cells in the cochlea duct (within the membranous labyrinth)
This mostly happens at a spot called the …
organ of corti - the strucutre of stuff that transmits the vibrations
High frequency sounds stimulate hair cells at the __ of the cochlea
base
Low frequency sounds stimulate hair cells at the __ of the cochlea
apex
Vibration of ____membrane results in movement of hair cells against _____membrane
Vibration of bascilar membrane results in movement of hair cells against tectorial membrane
The auditory/cochlea nerve is part of which canial nerve?
CN8
What is the mechanism for dynamic equilibrium?
movement of the endolymph through semicircular ducts into ampulla deflecting cupula and acivating hair cells (sensory receptors)
what is the mechanism of static equilibrium?
sesnsory receptors inn th utricle and saccule
movement of otolithic membrane due to gravity activates hair cells in utricle and saccule
