anatomy of ear

Question 1

functions of external ear?

Answer 1

receives sound waves

Question 2

functions of middle ear?

Answer 2

Transmits sound waves from air to bone
Amplifies by bone to bone
Transmits sound to inner ear

Question 3

functions of inner ear?

Answer 3

Sound waves converted to nerve impulses
Transmitted to CNS via acoustic nerve (CNVIII)
Vestibular organs

Question 4

what type of epithelium is the pinna

Answer 4

Stratified keratinized epithelium – skin.

Question 5

what type of cartilage is the pinna?

Answer 5

elastic cartilage

Question 6

where does the pinna get its blood supply from?

Answer 6

overlying Dense connective tissue/perichondrium

Question 7

what does the skin contain of th lateral 1/3 of external ear canal

Answer 7

containing ceruminous and sebaceous glands.

Question 8

true or false:

the ear has modified sweat gland producing wax

Answer 8

true

Question 9

does the medial 2/3 of external ear canal have hairs or produce wax?

Answer 9

no

Question 10

where does the skin grow from- external ear canal

Answer 10

umbo of the tympanic membrane outwards

Question 11

what are the three layers of the tympanic membrane?

Answer 11

Outer layer is continuous with skin of EAC.
Middle fibrous layer
Cuboidal epithelium

Question 12

what are the contents of the middle ear?

Answer 12

Ossicular chain
Oval window
Round window
Facial nerve (usually covered in bone)
Chorda tympani
Eustacian tube opening
Includes mastoid air cells

Question 13

what are the three ossicles of the year?

Answer 13

malleus
incus
stapes

Question 14

function of the ossicles

Answer 14

Conduct sound waves from tympanic membrane to inner ear via oval window

Question 15

function of middle ear

Answer 15

transduce vibration into nervous impulses

Question 16

function of the eustacian tube

Answer 16

1. Pressure equalisation
   Middle ear lined with respiratory epithelium
   Gas exchange happens
   Vacuum formed in middle ear
   Vacuum released on opening of eustacian tube
2. Mucus drainage

Question 17

otitis media with effusion

Answer 17

Eustacian tube not opening
negative pressure
Fluid drawn into middle ear
Fluid filled ear limits mobility of ossicular chain

Question 18

what is cholesteatoma?

Answer 18

Negative pressure
Sucks in Tympanic membrane
Retraction pocket
Normal skin growth
- umbo out
Over time
Enlarges retraction pocket
Skin no longer comes out of pocket
Enlarging ball of keratin into middle ear
Slowly destroys and invades structures

Question 19

complications of otitis media and cholesteatoma

Answer 19

Remember anatomical relations
Meninges
Middle cranial fossa
Facial nerve
Mastoid cavity
Inner ear
Sigmoid sinus/internal jugular vein

Question 20

6 segments of the facial nerve

Answer 20

Intracranial
Meatal segment (internal auditory meatus)
Labyrinthine segment
Tympanic segment (Fallopian tube. 10% of which are dehiscent. i.e within mucosa)
Mastoid segment
Extratemporal segment

Question 21

motor supply to the muscles of facial expression

Answer 21

Stapedius
Posterior belly of digastric
Stylohyoid

Question 22

5 branches of the facial nerve

Answer 22

Temporal, Zygomatic, Buccal, Marginal mandibular, Cervical

Question 23

what are the peripheral vestibular apparatus?

Answer 23

urticle
saccule
semicircular canals

Question 24

what are Semicircular canals responsible for?

Answer 24

detecting head rotation

Question 25

function of the saccule

Answer 25

detects linear acceleration in vertical plane

Question 26

functions of the urticle

Answer 26

detects linear acceleration in horizontal plane

Question 27

contents of external ear

Answer 27

Pinna and EAC

Question 28

contents of the middle ear

Answer 28

Tympanic membrane, ossicles

Lots of important things in and around

Question 29

contents of inner ear

Answer 29

Organ of corti – hearing

Semicircular canals/utricle/saccule – one part of balance