Ear

Question 1

What is the blood supply to the ear?

Answer 1

posterior auricular and superficial temporal As

Question 2

What is the innervation to the auricle?

Answer 2

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

Question 3

What occurs in auricular hematomas?

Answer 3

blood accumulates –> if you don’t remove –> abnormal cartilage = cauliflower ear

Question 4

What defines the external acoustic meatus?

Answer 4

extends from concha of auricle to tympanic membrane

lateral 1/3 = cartilage

medial 2/3 = bone

child’s is shorter than an adult’s

Question 5

What is otitis externa?

Answer 5

swimmer’s ear

infection of external acoustic meatus

risk factors:

excessive mousture, trauma, devices that occlude ear canal, etc

Question 6

Where is the cone of light always located on the tympanic membrane?

Answer 6

anterior and inferior

Question 7

What bone protects the incus and malleus?

Answer 7

epitympanic recess of temporal bone

Question 8

What are the parts of the tympanic membrane visible on examination?

Answer 8

pars flaccida = superior, posterior

pars tensa = rest of the surface

umbo

lateral process and handle of malleolus

Question 9

What is otitis media?

Answer 9

infection of the middle ear

inflammation and swelling of mucous membrane of tympanic cavity may block pharyngotympanic tub

TM red and bulging

Question 10

How is a tympanostomy tube placement performed?

Answer 10

post, inf incision

drain fluid

place tube

Question 11

What is the roof of the middle ear?

What does it separate the tympanic cavity from?

Answer 11

tegmen tympani

middle cranial fossa (if you have infection spread there, could get meningitis)

Question 12

What is the floor of the middle ear cavity?

What does it separate the tympanic cavity from?

Answer 12

tympanic part of temporal bone

internal jugular v

Question 13

What is the lateral wall of the middle ear cavity?

What does it separate the tympanic cavity from?

Answer 13

tympanic membrane

external ear

Question 14

What is the medial wall of the middle ear?

What does it separate the tympanic cavity from?

Answer 14

promontory of labyrinthine wall, oval window, round window, prominence of facial canal

inner ear

Question 15

What is the posterior wall of the middle ear cavity?

Answer 15

aditus to mastoud antrum, canal for the facial nerve

Question 16

What is the anterior wall of the middle ear cavity?

What does it separate the tympanic cavity from?

Answer 16

opening of pharyngotympanic tube and canal for tensor tympani

internal carotid a

Question 17

Where are the round and oval windows of the middle ear?

Answer 17

on the medial wall

oval = sup, post to promontory, stapes lies on it

round window = inferior to promontory

Question 18

What are the ossicles?

Answer 18

malleus

incus

stapes

Question 19

What are the parts of the malleus bone?

Answer 19

head - articulates w/ incus

neck - lies against pars flaccida

handle = embedded in tympanic membrane, *insertion of tensor tympani m

Question 20

What are the parts of the incus bone?

Answer 20

head - articulates w/ malleus

long limb - articulates w/ stapes

short limb

Question 21

What are the parts of the stapes bone?

Answer 21

head - articulates w/ incus

neck - *insertion for stapedius m*

base - inserts into oval window

2 limbs

Question 22

What is the tensor tympani m?

Answer 22

attaches to handle of malleus –> runs paralel to the pharyngotympanic tube

pulls malleus medially –> tenses tympanic membrane

prevents damage from loud sounds

Question 23

What is the stapedius m?

Answer 23

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

Question 24

Where is the chorda tympani in the ear?

What does it do?

Answer 24

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

Question 25

What is the tympanic n and what does it do?

Answer 25

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

Question 26

How does the lesser petrosal n leave middle ear and then the cranium?

Answer 26

goes thru roof of tympanic cavity --\> enters medial cranial fossa --\> leaves thru foramen ovale

Question 27

Where is the internal ear located?

Answer 27

in petrous part of the temporal bone

Question 28

What are the parts of the bony labyrinth?

Answer 28

cochlea = 1st turn, 2nd turn, cupula (large basal turn makes promontory) vestibule = oval and round windows semicircular canals = anterior, lateral, and posterior

Question 29

What is the bony labyrinth filled with? The membranous labyrinth?

Answer 29

bony = perilymph membranous = endolymph

Question 30

What are the parts of the membranous labyrinth

Answer 30

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

Question 31

What is the nerve in the cochlea? Where is it specifically embedded?

Answer 31

cochlear N = branch of CN 8 (vestibulocochlear n) embedded in basilar membrane