Anatomy & Physiology of the Ear

Question 1

What type of skin is found on the outside of the ear?

Answer 1

Stratified keratinising sqaumous epithelium

Question 2

What is the E.A.M. made up of?

Answer 2

Lateral 1/3 cartilage and skin

Medial 2/3 bone and skin

Question 3

What glands are unique to the ear and what do they produce?

Answer 3

Ceruminous & Sebaceous glands

Produce wax

Question 4

What type of skin makes up the external ear canal?

Answer 4

Stratified squamous epithelium

Question 5

What type of epithelium lines the middle ear?

Answer 5

Columnar ciliated epithelium Respiratory

Question 6

What are the three layers of the tympanic membrane and how does it appear?

Answer 6

Outer squamous epithelial
Middle fibrous connective tissue
Inner columnar ciliated mucus membrane

Transparent

Question 7

What is suppuration of the tympanic membrane?

Answer 7

Infection, can lead to the ear drum bursting and pus leaking out

Question 8

What is the epitympanum and what does it contain?

Answer 8

Upper portion of the tympanic cavity

Contains the head of the malleus and the body of the incus

Question 9

What is the hypotympanum?

Answer 9

Lower part of the cavity of the middle ear, in the temporal bone

Question 10

What causes a disruption of sound conduction?

Answer 10

Trauma
Chronic suppuration
Otosclerosis

Question 11

What is most important for sound conduction?

Answer 11

Ossicular chain

Question 12

What does otosclerosis do?

Answer 12

Stops the foot plate vibrating causing conductive hearing loss

Question 13

What does the middle ear contain?

Answer 13

Ossicles
Facial nerve
Chorda tympani

Question 14

What is the middle ear connected to?

Answer 14

Mastoid system of the temporal bone

Post nasal space via the eustachian tube

Question 15

What does the eustachian tube join and how does it open?

Answer 15

The middle ear to the nose

Muscle action

Question 16

What does the facial nerve pass through to reach the parotid gland?

Answer 16

Stylomastoid foramen

Question 17

What are the dangers from infection and trauma for the middle ear?

Answer 17

Intracranial sepsis
Facial nerve damage
Deafness
Dizziness

Question 18

What organ is responsible for balance and hearing in the middle ear?

Answer 18

Vestibulo-cochlear organ

Question 19

What is found in the bony labyrinth of the inner ear?

Answer 19

Cochlea
Vestibule
Semi-circular canal

Question 20

What is the membranous labyrinth made of?

Answer 20

Sensory epithelium

Question 21

What two types of fluid are found in the inner ear and where are they found?

Answer 21

Endolymph - Contained in the memrbanous labyrinth in the ear

Perilymph - Found in the space separating the membranous lymph from the osseous lymph

Question 22

How many turns of the cochlear are there and how many semi-circular canals are present?

Answer 22

2.5
&
3 - Lateral, Posterior & Anterior

Question 23

What is found in the cochlear duct?

Answer 23

Endolymph - It is membranous and rich in potassium

Question 24

What is the I.A.M.?

Answer 24

The junction between the inner ear and the brain stem

Question 25

What two cranial nerves are found in the I.A.M.?

Answer 25

Facial (CN VII) | Vestibulo-cochlear (CN VIII)

Question 26

What is the I.A.M. the clinical site of?

Answer 26

Acoustic neuroma | Vestibular schwannoma

Question 27

How cochlear cells produce a sound?

Answer 27

Produce electrical activity from the endolymph and perilymph which then becomes a neural impulse which travels to the brain along the cochlear nerve VIII

Question 28

In the cochlea, what frequencies are heard at what turns?

Answer 28

Basal turn - High frequency | Apical turn - Low frequency

Question 29

What type of hearing losses predominate in hearing losses?

Answer 29

Conductive losses - Low frequencies | Sensorineural losses - High frequencies

Question 30

What is audiometry?

Answer 30

Subjective test measuring amplitude or intensity of sound and frequency

Question 31

What is tympanometry?

Answer 31

Measure of tympanic membrane compliance involving middle ear and ear canal pressure

Question 32

What massively affects speech in relation to the ear?

Answer 32

Hearing impairment in the first four years of life

Question 33

What nerves innervate the ear?

Answer 33

Cervical nerve root branches Trigeminal (CN V) Glossopharyngeal (CN IX) Vagus (CN X)

Question 34

What is the effect of wax or physical obstructions on hearing loss?

Answer 34

Very minimal unless they impinge directly on the T.M.

Question 35

What has the biggest effect on hearing loss?

Answer 35

Loss of ossicular continuity - 55-60db | *Perforation of T.M. has a smaller effect - 30-35db