Clinically relevant anatomy of the ear

Question 1

Where are the organs of hearing & balance, facial nerve and vestibulocochlear nerve contained?

Answer 1

Petrous part of the temporal bone

Question 2

Function of the middle ear?

Answer 2

Amplifies and conducts sound waves to the internal ear

Question 3

Function of the external ear?

Answer 3

Collects and conveys sound waves to the tympanic membrane

Question 4

Function of the internal ear?

Answer 4

Converts sensory information on sound/balance into FLUID WAVES and conducts the APs towards the brain stem

Question 5

What is the internal ear?

Answer 5

The oval window to the internal acoustic meatus

Question 6

What is the external ear?

Answer 6

From the auricle to the tympanic membrane

Question 7

What is the middle ear?

Answer 7

From the tympanic membrane to the oval window

Question 8

Nerve supply to the superior parts of the EAM & most of the tympanic membrane

Answer 8

CNV3

Question 9

Nerve supply to the INFERIOR parts of the EAM & the tympanic membrane

Answer 9

CNX

Question 10

Lymphatic drainage of the ear?

Answer 10

Parotid and mastoid nodes –>
Deep cervical nodes –>
Thoracic duct/right lymphatic duct –>
Right venous angle

(mastoid nodes = post-auricular nodes)

Question 11

Where are the deep cervical nodes?

Answer 11

In the carotid sheath with the internal jugular vein

Question 12

Tuning fork for ear

Answer 12

512Hz

Question 13

Posteroinferiorly on tympanic membrane

Answer 13

Pars tensa

Question 14

Anteroinferiorly on tympanic membrane

Answer 14

Light reflex

Question 15

Most inwardly depressed part of the tympanic membane

Answer 15

Umbo

Question 16

Nerve supply to middle ear cavity, eustachian tube, nasopharynx, oropharynx and the tonsils

Answer 16

CNIX

Question 17

Nerve supply to middle ear cavity

Answer 17

CNIX

Question 18

Nerve supply to eustachian tube

Answer 18

CNIX

Question 19

Nerve supply to nasopharynx, oropharynx and tonsils

Answer 19

CNIX

Question 20

Nerve supply to external surface of tympanic membrane

Answer 20

CNV3 (auriculotemporal branch)

Question 21

Branch of V3 which supplies the external surface of the tympanic membrane?

Answer 21

Auriculotemporal branch

Question 22

Nerve supply to the INTERNAL surface of the tympanic membrane?

Answer 22

CNIX

Question 23

Doorway from mastoid antrum into the epitympanic recess

Answer 23

Aditus

Question 24

Mastoiditis

Answer 24

Commonly due to spread of infection from middle ear cavity via the aditus

Question 25

Which nerve passes through stylomastoid foramen and through internal acoustic meatus?

Answer 25

CNVII (facial nerve)

Question 26

Nerve for balance

Answer 26

Vestibular (branch of CNVIII)

Question 27

Nerve for hearing

Answer 27

Cochlear (branch of CNVIII)

Question 28

Cupula

Answer 28

Apex of spiral (on cochlea)

Question 29

Where is the membranous labryinth?

Answer 29

Within the bony labryinth

Question 30

What is perilymph?

Answer 30

Fluid that fills the bony labryinth | membranous labryinth floats in perilymph and this is in the bony labryinth

Question 31

Where do CNVII and CNVIII connect with the brainstem?

Answer 31

At the junctio nbetween the pons and medulla oblongata

Question 32

Where does the chorda tympani supply?

Answer 32

Supplies the tastebuds of the anterior 2/3rds of the tongue | -parasympathetic supply to the submandibular and sublingual salivary glands

Question 33

What does the tensor tympani do and which nerve is it supplied by?

Answer 33

Pulls on the handle of the malleus to tense the tympanic membrane -supplied by CNV3

Question 34

Smallest skeletal muscle in the body?

Answer 34

Stapedius

Question 35

What does stapedius do?

Answer 35

Reduces stapes movement to protect the internal ear from excessive noise (supplied by CNVII)

Question 36

This canal connects the internal acoustic meatus to the stylomastoid foramen

Answer 36

Facial canal

Question 37

Which nerve supplies the stapedius?

Answer 37

CNVII

Question 38

The facial nerve's base of skull course is through which bone?

Answer 38

Petrous temporal bone

Question 39

Extracranial course of CNVII?

Answer 39

Enters the posterior aspect of the parotid salivary gland and then divides WITHIN the gland into somatic motor branches for muscles of facial expression

Question 40

Muscle of the forehead

Answer 40

Frontalis (supplied by CNVII)

Question 41

Sphincter of eyelid

Answer 41

Orbicularis oculi (supplied by CNVII)

Question 42

Orbicularis oris

Answer 42

Sphincter of the lips | supplied by CNVII

Question 43

How to clinically test CNVII?

Answer 43

Frown Close eyes tightly Smile Puff out your cheeks