ENT

Question 1

what is the function of the the auditory ossicles?

Answer 1

transfer and amplify air vibrations into the inner ear to be processed as sound

Question 2

what is external acoustic meatus?

Answer 2

ear canal - starts from outer ear (conchae) and extends to middle ear

Question 3

tympanic membrane anatomical features?

Answer 3

lateral process of malleus
pars flaccida
pars tensa
cone of light

Question 4

what are abnormal TM signs?

Answer 4

Perforations
Tympanosclerosis - deposits of dense hyaline tissue on the middle ear mucous membrane
Red and bulging membrane
Retraction of the membrane

Question 5

what is microtia?

Answer 5

underdeveloped outer ear cartilage

Question 6

what is acoustic neuroma and signs of acoustic neuroma?

Answer 6

non-cancerous tumour which compresses against the vestibular nerve (CN VIII)

vertigo
hearing loss
tinnitus
absent corneal reflex (cotton wool)
these symptoms occur due to pressure symptoms on CN VIII

Question 7

structure of ear?

Answer 7

outer - pinna and ear canal (external acoustic meatus)

middle - tiny ossicles (stapes, incus, malleus)

inner - cochlea (converts sound waves into electrical impulses)

semicircular canals - resp for balance

Question 8

What is the structure and function of the external ear?

Answer 8

pinna/auricle - cartilaginous structure to support external ear

pinna function: directs sound waves towards opening of EAM

lobule - unknown function

EAM (Ear canal) - short curved tube that burrows through temporal bone, ends at TM

extrenal ear function: collects sound waves and channels them into the ear canal (external auditory meatus), where the sound is amplified. soundwaves travel to TM

Question 9

Describe the structure of the ear canal?

Answer 9

hair follicles - forms protective barrier w ear wax, stops foreign bodies from entering ear

ceruminous glands - make cerumen (ear wax) - prevent foreign objects from damaging the TM

Question 10

Describe the structure and function of TM

Answer 10

thin membrane which separates external ear from middle ear

shaped like cone, protruding into middle ear

Question 11

Describe the physiology of hearing

Answer 11

when sound waves reach the eardrum it vibrates and transmits the vibrations into ossicles of middle ear

Question 12

Describe the structure and function of the middle ear

Answer 12

air-filled cavity within the temporal bone

lateral wall: eardrum

internal (medial) wall: separates middle from inner ear

posterior wall: opening called mastoid antrum - connects middle ear w mastoid cavity within the temporal bone

roof: called epitympanic recess

anterior wall: opening for eustachian tube - connects middle ear to nasopharynx

Question 13

What is the function of the oval window?

Answer 13

thin membrane opening from middle ear to cochlear (inner ear)

Question 14

3 functions of Eustachian tube?

Answer 14

1. equalising pressure across TM
2. protecting middle ear from reflux of fluid from nasopharynx
3. clears out middle ear secretions

Question 15

How are sound vibrations transferred from eardrum to ossicles?

Answer 15

sound enters via outer ear → eardrum vibrates → handle of malleus rests on eardrum → base of stapes rests on oval window → oval window transmits vibrations to inner ear

so the order of vibration is as follows:

eardrum → malleus → incus → stapes → oval window → transfers vibrations to INNER EAR

Question 16

What are the 2 components of the labyrinth?

Answer 16

bony labyrinth: tough bony shell filled with perilymph

membranous labyrinth: inside bony labyrinth, filled with endolymph

the movement of perilymph & endolymph plays role in hearing & balance

Question 17

what are the 3 parts of the inner ear?

Answer 17

vestibule: central part of bony labyrinth

cochlea: fluid-filled, spiral-shaped cavity, plays role in hearing & auditory transduction

semicircular canals: 3 tiny fluid-filled tubes that help with balance

Question 18

Describe the 3 structures of the cochlea?

Answer 18

scala vestibuli - connects to middle ear via oval window - PERILYMPH

cochlear duct - houses organ of Corti - contains hearing receptors/hair cells - ENDOLYMPH

scala tympani - connected to middle ear via round window - PERILYMPH

Question 19

How does the organ of Corti transmit sound to the brain?

Answer 19

sound travels through external ear & ossicles of middle ear → when foot of stapes beats against the oval window → it transfers vibration to perilymph inside scala vestibuli → this forces the fluid into motion → this transmits to organ of Corti inside cochlear duct → hair receptors in cochlea convert these vibrations into an electrical impulse → this sent to auditory cortex via CN VIII

Question 20

Describe the 2 components of the apparatus of the inner ear?

Answer 20

responsible for balance
semicircular canals + 2 otolith organs

Question 21

What are the semicircular canals and otolith organs?

Answer 21

3 semicircular canals - perpendicular to each other - contain endolymph - opens into utricle

canal opens into ampulla - detect changes in head rotation - dynamic eqm

endolymph inside canals moves when head moves → hair cells fire electrical signal → signal detected by vestibular branch of CN VIII

Question 22

What are the otolith organs?

Answer 22

otolith organs: utricle & saccule - ENDOLYMPH - contains macule - contains balance receptor - detect changes in static eqm - detect head position in relation to gravity

Question 23

what is csf rhinorrhea halo sign from ear?

Answer 23

this is CSF - if this leaks from ear then indicates basal skull fracture

Question 24

what is ear discharge associated with?

Answer 24

usually middle ear infection