Ear Flashcards
external ear
all of external ear up to tympanic membrane
middle ear
tympanic membrane - innter ear
opens to pharynx through pharyngotympanic tube
internal ear
has to do with hearing and balance
auricle
external ear
collects sound waves
skin and elastic cartilage
connected with fascia on side of skull via auricular muscles
helix
outside curl of ear
antihelix
second ear fold inside of helix
antitragus
bump of cartilage opposite of tragus
intertragic notch
notch between tragus and antitragus
sensation from the ear is carried by which nerves?
auriculotemporal
grat auricular
tympanic membrane
separates external acoustic meatus from middle ear cavity
fibrous membrane
- layer of skin on lateral side
- mucosa on medial side
concave w central depression (umbo - distal aspect of handle of malleus)
anchored to bone via fibrotartilaginous ring
umbo
depression in central tympanic membrane - distal aspecct of handle of malleus
general sensation from most of external auditory meatus and external surface of tympanic membrane is carried by which nerve?
auriculotemporal branch of mandibular division of trigeminal (V3)
which nerves carry sensation from a portion of the external surface of the tympanic membrane and inferior aspect of the external auditory meatus?
facial(VII) and vagus (X)
What may explain a gag reflex in some people?
branches of facial (VII) and vagus (X) carrying sensation from external surface of tympanic membrane and inferior aspect of external auditory meatus
what nerve inntervates the internal surface of the tympanic membrane?
glossopharyngeal (IX)
name the walls of the tympanic cavity (middle ear)
superior - tegmental medial (promontory) lateral (tympanic membrane) inferior - jugular anterior - carotid posterior - mastoid
epitympanic recess
space caused by elevation in tegmental wall (superior) of tympanic cavity
promontory
convexity in medial wall of tympanic cavity caused by cochlear base
aditus
opening in mastoid wall (posterior) of tympanic cavity
leads to mastoid antrum
mastoid antrum
space posterior to tympanic cavity
communicates with mastoid air cells
oval (vestibular window)
in medial wall of tympanic cavity
covered by stapes
round (cochlear) window
in medial wall of tympanic cavity
covered by membrane
which nerve travels between malleus and incus
chorda tympani (facial VII)
tympanic nerve
branch of glossopharyngeal (IX)
forms tympanic plexus
carried sensory info in middle ear
part of it travels through tympanic cavity as lesser petrosal nerve
what are the purpose of the 2 openings in the anterior (carotid) wall of the typanic cavity
tensor tympani muscle
pharyngotympanic tube
what is the function of the pharyngotympanic tube
equalize pressure in middle ear
tensor tympani
attached to malleus
contract in response to loud sounds to protect ear from damage
N: mandibular trigeminal v3
stapedius
attached to stapes
contract in response to lound sounds to protect ear from damage
N: facial VII
what makes up the bony labyrinth of the inner ear
vestibule
semicircular canals
cochlea
ampullae
bulges at base of semicircular canals
endolymph
fluid inside membranous labyrinth
perilymph
fluid between bony and membranous labyrinth
utricle and saccule
membranous dilations inside the bony vestible
continuous with endolymphatic duct
each have specialized area of sensory epithelium = macula
macula
in utricle/saccule
specialized area of sensory epithelium
contain hair cells embedded in gelatinous layer covered by layer of crystals = otoconia/otoliths
otoconia/otoliths
calcium carbonate crystals in maculae
shift in position caused by moving head = hair cells stim to tell brain position of head
vestibular portion of vestibulocochlear nerve (VIII)
crista ampullaris
sensory area within ampulla of semicircular canals
contains hair cells with cilia embedded in gelatinous strucure (cupula)
what motion moves endolymph into anterior canal
nod
what movement moves endolymph into lateral canal
shaking head no
what movement moves endolymph into posterior canal
tilting head to side
modiolus
bony core around which the cochlea turns
apex of cochlea points
anterolaterally
cochlear duct
scala media
membranous portion of cochlea concerned with hearing
center
filled with endolymph
vestibular duct
scala vestibule
superior to chochlear duct
tympanic duct
scala tympani
inferior to cochlear duct
basilar membrane of ear
between cochlear duct and tympanic duct
spiral organ of Corti sits on here
organ of corti
sits on basilar membrane
rows of hair cells with cilia in contact with tectorial membrane - attached to bony projectionof modiolus
process of hearing
- basilar membrane oscillates in response to waves in endolymph in cochlear duct
- hair cells of organ of Corti move
- hair cells push against rigid tectorial membrane (against bony modiolus) = deformation
- deformation = relay info to brain via cochlear portion of vestibulocochlear nerve (VIII)
spiral gangion
within modiolus
contain cell bodies of the primary afferent neurons of the spiral organ
blood supply to bony labyrinth
anterior tympanic artery (maxillary)
stylomastiod (posterior auricular)
petrosal (middle meiningeal)
blood supply to membranous labyrinth
labyrinthine artery (anterior inferior cerebellar/basilar a ) travels thorugh internal auditory meatus with facial nerve and vestibulocochlear nerve)
