WEEK 7 - EAR

Question 1

list the two main functions of the ear

Answer 1

• hearing
• balance

Question 2

where is the ear primarily situated

Answer 2

temporal bone

Question 3

what part of the ear is not situated in the temporal bone

Answer 3

cartilaginous part of the auditory tube which is situated in a groove alongside the petrospenoidal suture

Question 4

list the components of the ear

Answer 4

• external ear
• eardrum
• middle ear
• inner ear

Question 5

function of external ear

Answer 5

collection of mechanical sounds vibrations

Question 6

function of ear drum

Answer 6

transmission, amplification

Question 7

middle ear function

Answer 7

transmission, amplificaton

Question 8

function of inner ear

Answer 8

cochlea, vestibule, semicircular canals > sensations

Question 9

how long is the external acoustic meatus

Answer 9

~24mm long

Question 10

what part of the ear is cartilaginous and bony

Answer 10

lateral one third > c
medial two third > b

Question 10

list the 6 boundaries of the middle ear

Answer 10

• lateral
• anterior
• roof
  -posterior
  -floor
  -medial

Question 11

what is in the lateral wall of the middle ear

Answer 11

tympanic membrane

Question 12

what is in the anterior wall of the middle ear

Answer 12

• auditory tube

Question 13

what is in the roof of the middle ear

Answer 13

tegmen tympani - thin bone seperating middle ear from the middle cranial fossa

Question 14

what is in the posterior wall of middle ear

Answer 14

• back of epitympanic recess leading into the aditus

Question 15

where is the chorda tympani nerve found

Answer 15

posterior wall of the middle ear

Question 16

what is in the floor of the middle ear

Answer 16

jugular wall
- jugular vein

Question 17

in the tympanic cavity, what does the pharynx connect via

Answer 17

auditory tube

Question 18

in the tympanic cavity, what does the mastoid air cells connect via

Answer 18

mastoid aditu

Question 19

what is contained in the epitympanic cavity

Answer 19

head of the malleus and part of the body of the incus are contained

Question 20

where does the chorda tympani nerve leave

Answer 20

~5mm above the stylomastoid foramen

Question 21

where does the chorda tympani exit va

Answer 21

petrotympanic fissure

Question 22

what nerve does the chorda tympani join with (hitchhike)

Answer 22

lingual nerve

Question 23

how many ossicles are there in the ear

Answer 23

three

Question 24

what are the 3 ossicles of the ear compose dof

Answer 24

dense compact bone covered with mucosa

Question 25

what type of joint is in the articulation between the incus and the malleus and stapes

Answer 25

synovial joint

Question 26

how do ossicles develop

Answer 26

endochondral ossification of the ends of the cartilage supporting pharyngeal arches

Question 27

where is the blood supply of the ear (tympanic plexus)

Answer 27

via the mucosa covering the ossicles which is in communication with the mucosa lining hte other parts of the tympanic cavity

Question 28

what size and shape are the ossicles

Answer 28

full sized at birth

Question 29

what are the small cracks or damage of the ossicles referred as

Answer 29

feebles

Question 30

list the muscles of tympanic cavity

Answer 30

tensor tympani
stapedius

Question 31

how do the muscles of the tympanic cavity work

Answer 31

reflex reponse to high intensity sounds
- muscle fibres contract and reduces the vibration of the ossicles which in turn reduces the intensity of the sound before it reaches the inner ear

Question 32

can the muscles of the tympanic cavity react to sudden noise such as gunshots

Answer 32

no, but it provides partial protection

Question 33

what type of muscle is tensor tympani and stapedius

Answer 33

skeletal muscle > contract involuntarily)

Question 34

where is the tensor tympani situated

Answer 34

within a bony canal above the cartilaginious auditory tube

Question 35

what is tensor tympani innervated by

Answer 35

medial pterygoid branch of V3 from CN5

Question 36

WHERE DOES THE MUSCULAR part of stapedius lies

Answer 36

in a canal in the posterior wall

Question 37

what is the stapedius innervted by

Answer 37

small branch of CN2 > nerve to stapedius

Question 38

list the two largest branches which supply the middle ear

Answer 38

• tympanic branch of the maxillary artery
• mastoid branch of posterior auricular arteries

Question 39

list the smaller branches of the middle ear

Answer 39

middle meningeal artery
- ascending pharyngeal artery
- artery of the pterygoid canal
- tympanic branches from the internal carotid artery

Question 40

where does the venous drainage of the middle ear returns to

Answer 40

to the pterygoid plexus of veins and the superior petrosal sinusu

Question 41

what is the auditory tubed lined with

Answer 41

respiratory mucosa

Question 42

where does the cartilaginous part of the auditory tube run

Answer 42

groove between petrous temporal bone and greater wing of sphenoid

Question 43

where does the auditory tube open into

Answer 43

lateral wall of nasopharynx

Question 44

is the auditory tube normally opened or closed

Answer 44

closed, but opens during swallowing, chewing etc

Question 45

what does the inner ear consists of

Answer 45

• bony labyrinth within the temporal bone

Question 46

what is the bony labyrinth of the inner filled with what fluid

Answer 46

perilymph - seperates bony labyrinth from membranous labyrinth

Question 47

what does the membranous labyrinth contains which type of fluid

Answer 47

endolymph

Question 48

what does the bony labyrinth consist of

Answer 48

vestibule
three semicircular canals
cochlea