The Ear Flashcards
what bone houses the vistibulocochlear apparatus
petrous part of temporal bone
what two cranial nerves exit the skull through the internal acoustic meatus
CN VII and VIII
what emerges through the stylomastoid foramen
the facial nerve
what are the three broad areas of the ear
external
middle
inner
what does the tympanic membrane separate
external ear from middle ear
what does the pharyngotympanic tube join
the middle ear to the nasopharynx
what is the function of the external ear
leads sound waves to tympanic membrane
what is the function of the middle ear
contains ossicles which mechanically transmit sound
what is the function of the inner ear
contains semi-circular canals and cochlea which convert the mechanical signals to electrical signals carried by CN VIII to the brain
what aspect of the external ear does the great auricular nerve supply
the medial surface, back of ear and helix and lobules
what part of the external ear does the auriculotemporal nerve supply
tragus and crus
what comprises the external acoustic meatus
lateral cartilagenous 1/3 and bony medial 2/3
what epithelium is present in the external acoustic meatus
stratified squamous epithelium
what glands are present in the external acoustic meatus
ceruminous glands
what is the function of the ceruminous glands
secretes earwax to keep foreign bodies away from tympanic membrane
what is the tympanic membrane held to the temporal bone by
fibrocartilaginous ring
what is the umbo of the tympanic membrane
the peak
what is the cone of light
caused by light of the otoscope which is characteristic of a healthy middle ear as there is no fluid accumulation
what is the middle ear
air filled chamber in petrous part of temporal bone which contains ossicles and two muscles
what two muscles are contained in the middle ear
tensor tympani and stapedius
what are ossicles
chain of mobile small bones
what is the maleus attached to
tympanic membrane
what are the three ossicles
maleus
incus
stapes
what is the structure of the stapes
kind of looks like a ring
what is the function of the ossicles
to increase force and decrease amplitude of vibrations from tympanic membrane
what is the function of the tensor tympani
dampens movement of tympanic membrane to protect ear from loud sounds
what is the function of the stapedius
dampens or resists movement of ossicles
innervation of tensor tympani
CN V3
innervation of stapedius
CN VII
what is the function of the auditory tube
pressure equalisation between middle ear and atmospheric pressure
what is a potential clinical consideration of the internal acoustic meatus
this is where CN VII and VIII exit and there can be a Schwonnoma here which could require surgery
what does the CN VII give off when it passes through the middle ear
greater petrosal nerve
what is the role of the greater petrosal nerve
carries parasympathetic fibres to pterygopalatine ganglion
what nerve is given off just before CN VII exits via the stylomastoid foramen
chorda tympani
what two blood vessels run proximal to the middle ear
internal carotid artery
internal jugular vein
where does the chorda tympani travel in relation to the tympanic membrane
travels deep to the upper portion of tympanic membrane
what does the mastoid antrum connect
the mastoid process and middle ear
what is conductive deafness
where there is an issue with transmission of the sound (mechanically) via the ossicles - NOT the nerve
where is the vestibulocochlear organ housed
inner ear
what is the bony labyrinth of the inner ear
semi-circular canals, cochlea and vestibule
what fluid is contained in the bony labyrinth
perilymph and endolymph
where does the CN VIII split into the vestibular and cochlear parts
after exiting the internal acoustic meatus
where does the cochlear part of CN VIII travel to
travels to the cochlea
where does the vestibular part of CN VIII travel to
semicircular canals
function of cochlear part
hearing
function of vestibular part
balance
