clinical anatomy of ear and taste

Question 1

what does the pinna (auricle) do?

Answer 1

collects soundwaves and funnels them into the external acoustic meatus

Question 2

function of the tympanic cavity

Answer 2

to conduct soundwaves in the air towards the fluid-filled cavities of the inner ear
-bone conduction mechanism of hearing

Question 3

what are the ossicles of the middle ear

Answer 3

malleus
incus
stapes

Question 4

why do the ossicles decrease in size laterally to medially

Answer 4

for amplification

Question 5

what is the tympanic cavity

Answer 5

an air-filled compartment surrounded by bone that is separated from the external ear by a thin tympanic membrane (tympanum)

Question 6

what type of joints are in the tympanic cavity

Answer 6

synovial

Question 7

what does the tensor tympani muscle do

Answer 7

• runs from the cartilaginous portion of the eustachian tube to handle of malleus
• dampens sound by reducing vibrations of tympanic membrane

Question 8

what is the tensor tympani muscle innervated by

Answer 8

CN V3 (occulomotor)
-reduces noise from chewing

Question 9

what does the strapedius muscle do

Answer 9

dampens sound by reducing vibrations of stapes on oval window

Question 10

what is the strapedius muscle innervated by

Answer 10

CN VII

Question 11

what do the palate muscles do to equalise pressure

Answer 11

open the eustachian tube

Question 12

what happens if atmospheric pressure is more than the tympanic cavity air pressure

Answer 12

the tympanic membrane pushed in

-reduced vibration of ossicles and potential for barotrauma

Question 13

what happens when atmospheric pressure is less than tympanic cavity pressure

Answer 13

tympanic membrane pushed out

• reduced vibration of ossicles
• potential for barotrauma

Question 14

what is general sensation of the tympanic cavity mucosa conveyed by

Answer 14

CN IX via tympanic plexus

Question 15

where is the otic capsule located

Answer 15

in the temporal bone

Question 16

what are the two labyrinths

Answer 16

bony labyrinth and membranous labyrinth

Question 17

what is the bony labyrinth similar to

Answer 17

• cavity of otic capsule
• similar to extracellular fluid
• filled with perilymph

Question 18

what is the membranous labyrinth

Answer 18

suspended within bony labyrinth

• similar to intracellular fluid
• filled with endolymph

Question 19

how does hearing work

Answer 19

• sound waves make tympanic membrane vibrate
• vibrations transmitted through ossicles
• footplate of stapes vibrates in oval window
• vibration of stapes creates pressure waves in perilymph
• hair cells in the cochlea are moved, APs stimulated and conveyed to brain by cochlear nerve
• pressure waves descend and become vibrations again
• pressure waves are dampened at the round window

Question 20

what do the receptor hair cells in the organ of corti do

Answer 20

detect auditory stimuli

Question 21

what is the cochlear duct suspended by

Answer 21

the spiral ligament

Question 22

the cochlear duct divides the cochlear canal into what two parts

Answer 22

• scala vestibuli

- scala tympani

Question 23

where do you test for conductive hearing loss

Answer 23

• external ear

- middle ear

Question 24

where do you test for sensorineural hearing loss

Answer 24

inner ear

Question 25

what type of movement change is the utricle responsible for

Answer 25

horizontal

Question 26

what type of movement is the saccule responsible for

Answer 26

verticle

Question 27

what detects angular movement change

Answer 27

semicircular ducts

Question 28

what are the three semicircular canals that orientate at right angles to each other

Answer 28

- anterior - posterior - lateral

Question 29

head movement effect on hair cells

Answer 29

it moves hair cells relative to the endolymph and causes depolarisation

Question 30

what is found in the internal acoustic meatus

Answer 30

- facial nerve - vestibulocochlear nerve - labyrinthine artery + veins

Question 31

what can facial nerve dysfunction cause

Answer 31

- dry eyes - dry mucosa - lack of taste in anterior 2/3rds of tongue - dry mouth - facial paralysis

Question 32

what is the course of the cranial portion of the facial nerve

Answer 32

- leaves brainstem at pontomedullary junction | - enters the internal acoustic meatus

Question 33

what is the course of the temporal portion of the facial nerve course

Answer 33

- travels through temporal bone in close relationship to middle ear - leaves the temporal bone through the stylomastoid foramen

Question 34

what is the course of the extratemporal portion of the facial nerve

Answer 34

- courses towards and through the parotid gland | - splits into 6 branches

Question 35

what does the chorda tympani do

Answer 35

it conveys taste from the anterior 2/3rds of the tongue | -branches into pre ganglionic parasympathetic fibres to submandibular ganglion

Question 36

where does chorda tympani branch from

Answer 36

the facial nerve in the facial canal

Question 37

what nerve provides taste and general sensory to the posterior 1/3rd of tongue

Answer 37

CN IX

Question 38

what nerve provides general sensory to anterior 2/3rd of tongue

Answer 38

CN V3

Question 39

what nerve supplies taste to anterior 2/3rds of tongue

Answer 39

CN VII

Question 40

what is the external ear composed of

Answer 40

- the cartilaginous pinna (auricle) | - external acoustic meatus (ear canal)

Question 41

what is the pinna formed by

Answer 41

elastic cartilage attached to the temporal bone and encased in skin

Question 42

what is the external acoustic meatus like in a child

Answer 42

short and straight

Question 43

what is the EAM like in an adult

Answer 43

curved

Question 44

name features of the tympanic membrane

Answer 44

- pars flaccida - umbo - cone of light - pars tensa

Question 45

what joins the auditory ossicles

Answer 45

small synovial joints

Question 46

what are the two parts of the tympanic cavity

Answer 46

tympanic cavity proper and the epitympanic recess

Question 47

what does the continuous layer of mucosa lining the middle ear cavities do

Answer 47

it delivers sensory information via the glossopharyngeal nerve

Question 48

features of the medial wall of the tympanic cavity

Answer 48

oval window - received footplate of stapes round window - dissipates forces from cochlear promontory - bump from the basal turn of cochlear facial canal - contains the facial nerve

Question 49

what are the features of the anterior wall of the tympanic cavity

Answer 49

- the eustachian tube is a connection of the middle ear and the nasopharynx - the chorda tympani passes between the incus and malleus and through the anterior wall traveling towards the infratemporal fossa

Question 50

what is the function of the eustachian tube

Answer 50

to equalise air pressure between the middle ear and nasopharynx

Question 51

where does the glossopharyngeal nerve supply sensory innervation to the mucosa of

Answer 51

- middle ear cavity - eustachian tube - nasopharynx - oropharynx - palatine tonsils

Question 52

function of internal ear

Answer 52

reception of sound and maintenance of balance

Question 53

function of the origin of corti

Answer 53

turns fluid vibrations into neural action potentials

Question 54

visceral motor function of facial nerve

Answer 54

- parasympathetic supply to lacrimal gland - parasympathetic supply to submandibular and sublingual gland - parasympathetic supply to minor glands of the nasal cavity and palate

Question 55

what is the oral cavity divided into

Answer 55

oral vestibule and oral cavity proper