Anatomy and histology of the ear

Question 1

in an otoscope view what does the sensory for the: Anterior portion

Answer 1

CN V3, Auriculotemporal Nerve

Question 2

in an otoscope view what does the sensory for the: posterior portion

Answer 2

C3 Great auricular nerve

Question 3

in an otoscope view what does the sensory for the: superior portion

Answer 3

CN VII

Question 4

in an otoscope view what does the sensory for the: inferior portion

Answer 4

CN X Arnold nerve

can cause the arnold cough reflex by touching this

Question 5

In the cough reflex what is the efferent nerve and what is the afferent nerve

Answer 5

efferent: Vagus and phrenic nerve
afferent: vagus Nerve

Question 6

what produces wax in the external auditory ear canal (external acoustic meatus)

Answer 6

ceruminous glands

Question 7

How is the External acoustic meatus broken down

Answer 7

outer 2/3 soft connective tissue and cartilage

inner 1/3 is skin on bone

only place in body where the skin and the periosteum and bone exist directly on top of each other

no connective tissue

therefore bleeds easily

Question 8

what is the tympanic membrane made up

Answer 8

semitransparent membrane

outside layer lined with stratified squamous epithelium

inside layer lined with simple cuboidal epithelium

has concavity

moves with sound and transmits to ossicles

Question 9

Parts of the tympanic membrane

Answer 9

Handle of malleus
Umbo
Pars flaccida
anterior and posterior malleolar fold
cone of light
annulus
Pars tensa

Question 10

what quadrant is the cone of light found in

Answer 10

2nd quadrant where the innervation is done by Vagus Nerve

Question 11

What are the walls of the tympanic cavity

Answer 11

roof (superior): Tegmental wall
floor (inferior): jugular wall
Laterally: membranous wall
Medially: Labyrinthine wall
Posteriorly: mastoid wall
anterior: carotid wall

Question 12

what are the two parts of the tympanic cavity

Answer 12

Tympanic cavity proper

Epitympanic recess

Question 13

What are the three ossicles in the tympanic cavity and how are they attached

Answer 13

Malleus which is attached to the tympanic membrane
Incus in the middle
stapes that attaches to the oval window

Question 14

What nerves travel through the tympanic cavity

Answer 14

Tympanic nerve (CN IX)
Tympanic plexus
Lesser petrosal nerve
Facial nerve (runs next to in the labyrinthine wall)
chorda tympani

Question 15

what makes up the pharyngotympanic tube and what is its function

Answer 15

Connects the tympanic cavity (middle ear) with the nasopharynx

distal 2/3 boney
proximal 1/3 catilage

functions to equalize the pressures
-creates that ear popping sensation

Question 16

What muscles expand the pharyngotympanic tube

Answer 16

Levator veli palatine: contracts longitudinally which pushes against one wall

TEnsor veli palatine: pulls on the other wall

Question 17

how much does the ossicles amplify the force on the tympanic membrane

Answer 17

10x

Question 18

Action and innervation of the tensor tympani muscle

Answer 18

Pulls on handle of the malleolus to tense membrane and reduce amplitude

inn: CN V

Question 19

Action and innervation for the stapedius muscle

Answer 19

Pulls stapes posteriorly tightening annular ligament attaching it to the window

reduces oscillatory range and prevents excessive movement of stapes

inn: CN VII

Question 20

What does it mean if the tympanic membrane is tight

Answer 20

Need more energy to make vibration (reduces amplitude)

Question 21

What is the bony labyrinth

Answer 21

This is the cavity within the petrous region of the temporal bone

it is lined with endosteum and is seperated from the membranous labyrinth by perilymph

is considered the canals

Question 22

what is the membranous labyrinth and its two functions

Answer 22

made of small sacs and tubes within bony labyrinth

forms a continuous space enclosed with epithelium

2 sections with two different jobs

• cochlear duct
• utricle, saccule, semicircular ducts

is considered the ducts

Question 23

what are the three soft tissue canals that make up the cochlear duct

Answer 23

scala media : middle compartment that contains endolymph
-borders vestibular membrane, tectorial membrane, basilar membrane and the stria vascularis (makes endolymph)

Scala vestibuli: contains perilymph
moved by stapes at the oval window and is continuous with the scala tympani

scala tympani: connected to the round
full of perilymph

Question 24

where is the organ of corti located

Answer 24

found on the floor of the scala media resting on the basilar membrane

Question 25

WHat does the outer spiral lamina do

Answer 25

inner spiraling bony shelf that serves to support the tectorial membrane and the spiral ganglia

Question 26

What is the organ of corti and how does it work

Answer 26

composed of haircells, inner and outer phalangeal cells (support cessl) and pillar cells (support cells) one row of inner hair cells 3 rows of outer hair cells when the basilar membrane vibrates with sound it causes the stereocila attached to the tectorial membrane to move opening or closing K+ channels

Question 27

What is the function of the external ear

Answer 27

catches sound waves and directs them to the external auditory meatus and then to the tympanic membrane can also check an individuals temperature here

Question 28

What is the function of the middle ear

Answer 28

THe middle ear takes sound waves and turns it into physical movement also is important in changing the volume of the ear by tensing or relaxing the tympanic membrane also important in equalizing the pressure in the ear and nasal cavity

Question 29

What is the inner ears function

Answer 29

The inner ear is responsible for balance also is important for taking external sound waves and transforming them into usable information fro the brain

Question 30

The path of the sound wave when it enters the cochlea

Answer 30

1) stapes moves the oval window causing fluid pressure wave formation in the perilymph of the scala vestibuli 2) wave distorts the vestibular membrane causing pressure wave within the endolymph of the scala media 3) this displaces the basilar membrane and distorts sterocila of hair cells 4) pressure in the perilymph is transfered to scala tympani and exits via the round window

Question 31

How do the semicircular canals and ampulla work

Answer 31

there are three canals in three different axis -Ant-sagital -post- Coronal transverse- horizontal endolymph is filled and it is connected to the utricle at the end of the canals they have aampulla which has a gelatinous like cap called a cupulla there are innervated hair cells with sterocilla that are attached to the cupulla so that if the cupulla moves it moves the haircells serve as sensors for rotational velocity

Question 32

What is found in a utricle and a saccue

Answer 32

Vestibule contains a saccule and utricle each contain a macula -this is comprised of a cluster of hair cells with stereocilia with overlying gelatinous membrane called the otolithic membrane the otolithic membrane is then covered with calcium carbonate/protein crystals called otoconia

Question 33

What is the purpose of the utricle

Answer 33

linear acceleration and head tilts in horizontal plane | -U trip forward

Question 34

What is the purpose of the saccule

Answer 34

Linear acceleration and the head tilts in vertical plane | suck up

Question 35

what happens if the stereocilia move towards the kinocilium

Answer 35

there is a depolarization because of the opening of the K+ channels

Question 36

What happens if the stereocilia move away from the kinocilium

Answer 36

there is hyperpolarization because of the closing of the K + channels

Question 37

What drug causes ototoxicity to these hair cells

Answer 37

some types of antibiotics

Question 38

Charachteristics of Perilymph

Answer 38

Composition similar to CSD, High in Na+ and low in K+ and protein drains via the perilymphatic duct into the subarachnoid space originates from periosteum between Bony and membranous labytinths

Question 39

Characteristics of endolymph

Answer 39

High in K+ and protein but low in Na+ originates from stria vascularis Drains via endolymphatic duct into venous sinuses found within membranous labyrinth and in the corticolymphatic space

Question 40

What happens if the perichondrium is sheared off the elastic cartilage in the external ear

Answer 40

get hematoma and necrotic cartilage then you gen cartilage growth via chondrogenesis presents as cauliflower ear

Question 41

Damage to tympanic membrane

Answer 41

often due to: medial ear pressure because of fluid or barotrauma most heal but need follow up perhaps with antibiotics

Question 42

Mastoiditis

Answer 42

Infection of mastoid cells can spread into cranial fossa via petrosquamous cranial suture treated with antibiotics

Question 43

Otitis media

Answer 43

Ear infection ear ache with possible fluid or pus in middle ear due to inflammation or infection tympanic membrane appears red and bulged fluid maybe visible through membrane untreated can impair hearing and scarring of auditory ossicles

Question 44

Menieres syndrome

Answer 44

experience dizziness, vertigo, high pitched rushing or roaring sound (tinnitus) and fluctuating hearing loss associate with increase endolymph volume leading to abnormal signaling treat with medication or surgical ablation similar symptoms to viral labyrinths but are resolved within a week

Question 45

hearing loss

Answer 45

lots of causes conductive hearing loss in outer or inner ear: fluid build up, otits, excessive wax, otoscleosis sensorineural hearing loss: reduction in sound level and/ or fidelity due to damage to inner ear or auditory nerve affects hearing at different frequencies and intensities -age related -noise induced Central hearing loss: problem in CNS