Ear Flashcards
What is the blood supply to the ear?
posterior auricular and superficial temporal As
What is the innervation to the auricle?
Great auricular N (C2, C3) –> front/medial surface of outer ear
lesser occipital n (C2, c3) –> posterior surface of ear
Facial N –> little spots in concha
auriculotemporal (V3) –> tragus, ant wall external acoustic meatus, 2/3 tympanic membrane
Auricular branch of vagus n –> most of concha, posterior wall ear canal, 1/3 tympanic membrane
What occurs in auricular hematomas?
blood accumulates –> if you don’t remove –> abnormal cartilage = cauliflower ear
What defines the external acoustic meatus?
extends from concha of auricle to tympanic membrane
lateral 1/3 = cartilage
medial 2/3 = bone
child’s is shorter than an adult’s
What is otitis externa?
swimmer’s ear
infection of external acoustic meatus
risk factors:
excessive mousture, trauma, devices that occlude ear canal, etc
Where is the cone of light always located on the tympanic membrane?
anterior and inferior
What bone protects the incus and malleus?
epitympanic recess of temporal bone
What are the parts of the tympanic membrane visible on examination?
pars flaccida = superior, posterior
pars tensa = rest of the surface
umbo
lateral process and handle of malleolus
What is otitis media?
infection of the middle ear
inflammation and swelling of mucous membrane of tympanic cavity may block pharyngotympanic tub
TM red and bulging
How is a tympanostomy tube placement performed?
post, inf incision
drain fluid
place tube
What is the roof of the middle ear?
What does it separate the tympanic cavity from?
tegmen tympani
middle cranial fossa (if you have infection spread there, could get meningitis)
What is the floor of the middle ear cavity?
What does it separate the tympanic cavity from?
tympanic part of temporal bone
internal jugular v
What is the lateral wall of the middle ear cavity?
What does it separate the tympanic cavity from?
tympanic membrane
external ear
What is the medial wall of the middle ear?
What does it separate the tympanic cavity from?
promontory of labyrinthine wall, oval window, round window, prominence of facial canal
inner ear
What is the posterior wall of the middle ear cavity?
aditus to mastoud antrum, canal for the facial nerve
What is the anterior wall of the middle ear cavity?
What does it separate the tympanic cavity from?
opening of pharyngotympanic tube and canal for tensor tympani
internal carotid a
Where are the round and oval windows of the middle ear?
on the medial wall
oval = sup, post to promontory, stapes lies on it
round window = inferior to promontory
What are the ossicles?
malleus
incus
stapes
What are the parts of the malleus bone?
head - articulates w/ incus
neck - lies against pars flaccida
handle = embedded in tympanic membrane, *insertion of tensor tympani m
What are the parts of the incus bone?
head - articulates w/ malleus
long limb - articulates w/ stapes
short limb
What are the parts of the stapes bone?
head - articulates w/ incus
neck - *insertion for stapedius m*
base - inserts into oval window
2 limbs
What is the tensor tympani m?
attaches to handle of malleus –> runs paralel to the pharyngotympanic tube
pulls malleus medially –> tenses tympanic membrane
prevents damage from loud sounds
What is the stapedius m?
inside pyramidal eminence on posterior wal
inserts on neck of stapes –> pulls stapes posteriorly and tilts base in oval window
prevents damage from loud sounds
Where is the chorda tympani in the ear?
What does it do?
goes through middle ear - runs medial to handle of malleus over tensor tympani
branch of facial N w/ presyn PS –> thru mid ear –> thru petrotympanic fissure (btw tympanic and petrous parts of temporal bone) –> joins lingual N (V3) –> synapse in submandibular ganglion –> to glands
What is the tympanic n and what does it do?
branch of glossopharyngeal n (9)
gives rise to tympanic plexus (on the medial wall of middle ear) –> gives rise to lesser petrosal n
presynaptic PS –> thru tympanic and lesser petrosal –> synapses at otic ganglion –> auriculotemporal n –> innervates parotid gland
How does the lesser petrosal n leave middle ear and then the cranium?
goes thru roof of tympanic cavity –> enters medial cranial fossa –> leaves thru foramen ovale
Where is the internal ear located?
in petrous part of the temporal bone
What are the parts of the bony labyrinth?
cochlea = 1st turn, 2nd turn, cupula (large basal turn makes promontory)
vestibule = oval and round windows
semicircular canals = anterior, lateral, and posterior
What is the bony labyrinth filled with?
The membranous labyrinth?
bony = perilymph
membranous = endolymph
What are the parts of the membranous labyrinth
communicating sacs and ducts that are suspended in bony labyrinth
vestibular: utricle (larger, closer to simicurcular), saccule
semicircular ducts (anterior, post, and lateral)
cochlear labyrinth w/ cochlear duct
What is the nerve in the cochlea?
Where is it specifically embedded?
cochlear N = branch of CN 8 (vestibulocochlear n)
embedded in basilar membrane
