Anatomy of the Ear Flashcards
what is the pterion?
the thinnest part of the skull
the sqaumous part is superior/inferior to the petrous part
sqaumous is superior
petrous is inferior
identify these structures
which bones form the base of the skull?
n.b- as if looking down
frontal
ethmoid
sphenoid
temporal
occipital
what are the boundaries of eh external ear?
auricle to tympanic membrane
what is the function of the external ear?
collects and conveys sounds waves to tympanic membrane
what are the boundaries of the middle ear?
tympanic mebrane to oval window
what is the function of the middle ear?
amplifies and conducts sound waves to the internal ear
the eustachian tube belongs to which part of the ear?
middle ear
what are the boundaries of the internal ear?
oval window to internal acoustic meatus
what is the function of the internal ear?
converts special sensory information into fluid waves then APs and conducts these to the brain
what is the auricle?
visible part of the ear
where are three features of the auricle?
helix
tragus
ear lobe
what are some lympthnodes in the head and neck that the auricle drains to?
parotid lymph nodes
mastoid lymph nodes
superficial cervical lymph nodes
auricle lymphatic drainage all eventually drians to where?
deep cervical lymph nodes (in carotid sheath)
thoracic duct or right lymphatic duct
the external ear is made up of elastic cartilage true/false?
true- avascular
earwax is produced by what ?
ceruminous glands
an otoscope allows you to examine what?
the EAM and tympanic membrane
the EAM is curved/straight in children?
sraight in children
curved in adults
when perfroming an otoscope exam how should you pull the ear in children and aduls?
posteroinferiorly in children
posterosuperiorly in adults
what is the pars flaccida?
thinnest part of tympanic membrane- found superiorly
what is the umbo?
most inwardly depressed part of tympanic membrane
what is the thickest part of the tympanic membrane?
pars tensa
the external surface of the typanic membrane is innervated by what?
CN V3
internal surface- CN IX
glossopharyngeal nerve provides sensory innervation to what?
middle ear cavity
eustachian tube
nasopharynx
osopharynx
tonsils
what are the auditory ossicles?
3 bones of the middle ear
the auditory ossicles articulate via what joints?
synovial joints
handle of ______ adherent to internal aspect of tympanic mebrane creates the umbo
malleous
the ______ recess is superior to the tympanic membrane
epitympanic recess
what in the ear is also known as the ‘stirrup’
stapes
the base (footplate of the stapes) fits into what?
the oval window
what si the function of the stapedius muscle?
reduces stapes movement to protect the internal ear from excessive noise
describe the path of the facial nerve through petrous temporal bone
internal acoustic meatus
facial canal of petrous temporal bone
stylomastoid foramen
the facial nerve gives off a branch just before reaching the stylomastoid foramen. What is this branch called?
chorda tympani
loss of this structure in the cheeks is a clinical sign of malnutrition
loss of buccal fat pad
lacerations across this part of the lip must be carefully sutured by a specialist
vermillion border of the iips
what can you ask a patient to do to clinically test muscles of facial expression?
frown
close eyes tightly
smile
puff out cheeks
what conditon affects CN VII resulting in the inability to use your facial muscles?
Bells palsy
what are the two parts of the vestibulocochlear nerve?
cochlear nerve- hearing
vestibular nerve- balance
the internal ear is contained within what?
Otic capsule
define bony labrynth
sapce within the otic capsule filled with perilymph
perilymph is similar ot extra/intracellular fluid?
perilymph similar to extracellular fluid
endolymph similar to intracellular fluid
endolymph is found where?
membranous labyrinth suspended inside perilymph of bony labyrinth
what is the cupula of the cochlea?
apex of spiral
APs from the cochlear duct are conducted to the brainstem in what nerve?
cochlear nerve
APs in the semicircular ducts are conducted to the brainstem in what nerve?
vestibular nerve
what is the cochlear duct?
long baloon like structure within cochlea filled with perilympth
what are the semicircular ducts?
inter-linked balloon like structures within semicircular canals filled with endolympth
describe sound transmission (7)
- sound waves make tympanic membrane vibrate
- vibrations transmitted through ossicles
- base of stapes vibrates in oval window
- vibration of stapes creates pressure waves in perilympth
- hair cells in cochlea are moved nueotransmitter released cochlear nerve picks up APs
- pressure waves descend and become vibrations again
- pressure waves are dampened at roudn window
damage to the facial nerve could present with what?
struggles with facial expression
dry mouth/eyes
loss of taste from ant 2/3rds of tongue
n.b usually ipsilateral i.e right side loss= right side symtpoms
