Clinical Anatomy of the Ear

Question 1

What is the thinnest part of the skull?

Answer 1

Pterion

Question 2

What is the pterion a suture between?

Answer 2

Frontal, parietal, temporal and sphenoid bones

Question 3

What bones are found in the anterior cranial fossa?

Answer 3

Frontal, ethmoid and sphenoid

Question 4

What bones are found in the middle cranial fossa?

Answer 4

Sphenoid and temporal

Question 5

What bones are found in the posterior cranial fossa?

Answer 5

Temporal and occipital

Question 6

Identify each of the base of skull foraminae

Answer 6

Question 7

What is the only part of the anterior cranial fossa where a nerve passes through?

Answer 7

Cribiform plate of ethmoid

Question 8

Which nerves pass through the superior orbital fissure?

Answer 8

CNs III, IV, V1 and VI

Question 9

CN V2 passes though what base of skull foramen?

Answer 9

Foramen rotundum

Question 10

CN V3 passes though which base of skull foramen?

Answer 10

Foramen ovale

Question 11

Which cranial nerves pass through the internal acoustic meatus?

Answer 11

CNs VII and VIII

Question 12

CNs IX, X and XI all pass through which base of skull foramen?

Answer 12

Jugular foramen

Question 13

Which cranial nerve passes through the hypoglossal canal?

Answer 13

CN XII

Question 14

What are the borders of the external ear?

Answer 14

Auricle to tympanic membrane

Question 15

What are the borders of the middle ear?

Answer 15

Tympanic membrane to oval window (including eustachian tube)

Question 16

What are the borders of the internal ear?

Answer 16

Oval window to internal acoustic meatus

Question 17

Most of the auricle is supplied by which nerves?

Answer 17

C2/C3 spinal nerves

Question 18

Which nerves supply the external acoustic meatus?

Answer 18

CN V3 superiorly

CN X inferiorly

Question 19

The skeleton of the external ear is formed from which bone?

Answer 19

Temporal bone

Question 20

To examine the tympanic membrane in a child, the auricle should be pulled posterosuperiorly/posteroinferiorly and in an adult posterosuperiorly/posteroinferiorly

Answer 20

Child - posteroinferiorly

Adult - posterosuperiorly

Question 21

What nerves supply sensory innervation to the tympanic membrane?

Answer 21

External surface - CN V3

Internal surface - CN IX

Question 22

Identify the bones of the middle ear

Answer 22

Question 23

The epitympanic recess is superior/posterior and the tympanic cavity proper is superior/posterior to the tympanic membrane

Answer 23

Epitympanic recess - superior

Tympanic cavity proper - posterior

Question 24

What does the eustachian tube connect?

Answer 24

Tympanic cavity proper to nasopharynx

Question 25

What is the aditus?

Answer 25

Opening in epitympanic recess that connects to mastoid antrum

Question 26

The facial nerve travels directly from the CNS to what structure?

Answer 26

Internal acoustic meatus

Question 27

The facial nerve gives off the chorda tympani before it moves through which structure?

Answer 27

Stylomastoid foramen

Question 28

Once the facial nerve has given off the chorda tympani it is purely somatic motor/sensory and supplies muscles of facial expression/mastication

Answer 28

Motor Facial expression

Question 29

What nerve controls the inner ear?

Answer 29

Vestibulocochlear

Question 30

Which branches of the vestibulocochlear nerve control hearing and balance?

Answer 30

Cochlear nerve - hearing Vestibular nerve - balance

Question 31

What are the spaces within otic capsules called?

Answer 31

Bony labyrinths

Question 32

What do bony labyrinths contain?

Answer 32

Perilymph fluid

Question 33

What is suspended within perilymph fluid?

Answer 33

Membranous labyrinth containing endolymph fluid

Question 34

What structure sends APs to the brainstem via the cochlear nerve?

Answer 34

Cochlear duct

Question 35

What structure within semicircular canals sends APs to the brainstem via the vestibular nerve?

Answer 35

Semicircular duct

Question 36

How does sound reach the brain?

Answer 36

Tympanic membrane vibrates causing stapes base to vibrate creating pressure waves in perilymph that causes hair cells in the cochlea to move stimulating APs that are conveyed to brain via cochlear nerve