A28 - Clinical Anatomy of the Ear

Question 1

what is the thinnest part of the skull that is a H-shape and joins the frontal, parietal, temporal and sphenoid bones?

Answer 1

pterion

Question 2

what 2 parts of bone make up the temporal bones?

Answer 2

squamous and petrous

Question 3

what nerves are contains in the temporal bone?

Answer 3

facial (CN VII)

vestibulocochlear (CN VIII)

Question 4

what is the function of the external ear ?

Answer 4

collects and conveys sound waves to tympanic membrane

Question 5

what are the borders of the external ear ?

Answer 5

auricle to the tympanic membrane via the external acoustic meatus

Question 6

what is the function of the middle ear ?

Answer 6

amplifies and conducts sound waves to the internal ear

Question 7

what are the boundaries of the middle ear ?

Answer 7

tympanic membrane to the oval window

Question 8

what important structure which connects the ear to the nasopharynx does the middle ear contain?

Answer 8

eustachian tube

Question 9

what is the function of the internal ear ?

Answer 9

converts special sensory information

• into fluid waves
• then APs
• conducts APs to the brain

Question 10

what are the boundries of the internal ear ?

Answer 10

oral window to the internal acoustic meatus

Question 11

what parts of the skeleton make up the external ear?

Answer 11

temporal bone

Question 12

what type of cartilage is the external ear made of?

Answer 12

elastic cartilage

Question 13

how does elastic cartilage gain the nutrients it requires?

Answer 13

avascular so gets nutrients from the skin and mucosa surrounding it

Question 14

when injecting anaesthetic near the ear what should this not contain?

Answer 14

adrenaline

Question 15

how does the ear canal produce earwax?

Answer 15

via ceruminous glands

Question 16

what is the sensory supply of back of the ear, the helix and the ear lobe?

Answer 16

C2,3 - great auricular

Question 17

what area of the ear does the CN Va (mandibular nerve)?

Answer 17

superior parts of the external acoustic meatus and most of the tympanic membrane

Question 18

what is the sensory supply to the inferior part of the EAM and tympanic membrane?

Answer 18

CN X - branch of the vagus nerve called alderman nerve

Question 19

what is the lymphatic drainage of the lateral surface of the superior half of the ear ?

Answer 19

parotid lymph nodes

Question 20

what is the lymphatic drainage of the cranial surface of the superior half of the ear ?

Answer 20

mastoid lymph nodes (deep cervical lymph nodes?

Question 21

what is the lymphatic drainage of the rest of auricle including the lobe?

Answer 21

superficial cervical lymph nodes

Question 22

what is the overall drainage of the lymph of the overall ear?

Answer 22

deep cervical lymph nodes > thoracic duct or right lymphatic duct > venous angle

Question 23

what is a otoscopic examination?

Answer 23

examination of the EAM and tympanic membrane

Question 24

Which direction would you pull a child’s ear during an otoscopic examination

Answer 24

Posteroinferiorly

Question 25

Which direction would you pull a adult's ear during an otoscopic examination?

Answer 25

Posterosuperiorly

Question 26

what are the characteristics of a child's EAM?

Answer 26

short and straight

Question 27

what are the characteristics of an adults EAM?

Answer 27

curved

Question 28

what is the most inwardly depressed part of the tympanic membrane?

Answer 28

umbo

Question 29

what is the thin part of the tympanic membrane that sits superiorly?

Answer 29

pars flaccida

Question 30

what is the thick part of the tympanic membrane which sits posteroinferiorly?

Answer 30

pars tensa

Question 31

What innervates the external surface of the tympanic membrane?

Answer 31

CN V3 (auriculotemporal nerve)

Question 32

What innervates the internal surface of the tympanic membrane?

Answer 32

CN IX - glossopharyngeal

Question 33

What does the glossopharyngeal nerve supply sensory innervation to?

Answer 33

- middle ear cavity - eustachian tube - nasopharynx - oropharynx - tonsils

Question 34

what connects the tympanic cavity to the lateral wall of the nasopharynx>

Answer 34

eustachian tube

Question 35

what causes referred pain of tonsilitis or pharyngisits ?

Answer 35

eustachian tube

Question 36

In what part of the ear are the malleus, incus and stapes bones?

Answer 36

Middle ear

Question 37

what are the 3 auditory ossicles?

Answer 37

malleus icnus stapes

Question 38

What two muscles are in the middle ear?

Answer 38

Stapedius and tensor tympani

Question 39

What connects the middle ear cavity to the nasopharynx?

Answer 39

Pharyngotympanic Tube

Question 40

What type of joints do the auditory ossicles articulate by?

Answer 40

Synovial

Question 41

What creates the umbo of the tympanic membrane?

Answer 41

Handle of Malleus

Question 42

What branch of the facial nerve passes through the tympanic cavity?

Answer 42

Chorda Tympani

Question 43

What muscle reduces the stapes movement? It is the tinniest skeletal muscle in the body and is supplied by CN VII)

Answer 43

Stapedius

Question 44

what is the right promontory?

Answer 44

bony swelling on the medial wall formed hy the cochlea of the internal ear

Question 45

what is the aditus?

Answer 45

doorway into the mastoid antrum form he epitympanic recess

Question 46

what causes mastoditis?

Answer 46

spread of infection to the mastoid air cells from the middle ear cavity

Question 47

what is the pathway of the facial nerve through the middle ear cavity?

Answer 47

1. comes from the pons-medullary junction and exits via the internal acoustic meatus 2. travels in the facial canal of teh petrous temporal bone 3. then exits via the stylomastoid foramen

Question 48

what is the thinnest skeletal muscle in the body which is supplies by CN VII that reduces stapes movement to protect the internal ear from excessive noise?

Answer 48

the right stapedius muscle

Question 49

what is the extracranial course of the facial nerve?

Answer 49

1. exits via the stylomastoid foramen | 2. branches off to supple muscles of facial expression

Question 50

what is the pathway of the chorda tympani?

Answer 50

1. branches from the facial nerve and exits the skull via stylomastoid foramen 2. follows the lingual branch of CN V3 to synapse at the submandibular ganglion 3. post-ganglionic fibres then supple the submandibular and sublingual glands

Question 51

where is the internal ear located?

Answer 51

petrous part of the temporal bone

Question 52

what nerve supplies the internal ear?

Answer 52

CN VIII - vestibulocochlear

Question 53

what are the two parts of CN VIII?

Answer 53

- cochlear nerve for hearing | - vestibular nerve for balance

Question 54

what is contained in the otic capsule?

Answer 54

bony labyrinth

Question 55

what fills the bony labyrinth?

Answer 55

perilymph (similar to extracellular fluid?

Question 56

what is suspended within the perilymph of the bony labyrinth?

Answer 56

- membranous labyrinth - communicating sacs - endolymph fluid

Question 57

what part of the otic capsule is resposnsibel for hearing?

Answer 57

cochlea - sprial which has 2 turns ending in an apex

Question 58

what part of the otic capsule is responsible for balance?

Answer 58

the three semi-circular canals

Question 59

what is teh long balloon like structure within the cochlea filled with endolymph?

Answer 59

cochlear duct

Question 60

what are the inter-linked balloon like structures within the semi-circular canals filled with endolymph?

Answer 60

semi-circular ducts

Question 61

what are clusters of hair cells in the ear?

Answer 61

maculae

Question 62

what do semi-circular ducts detect?

Answer 62

angular movement changes

Question 63

what detects linear movement changes?

Answer 63

utricle and saccule

Question 64

Descibe the 6 stages of sound transmission?

Answer 64

1. Sound waves make the tympanic membrane vibrate 2. Vibrations transmitted through ossicles 3. Base of stapes vibrates in oval window 4. Vibration of stapes creates pressure waves in perilymph 5. Hair cells in the cochlea are moved, neurotransmitter is released, Aps stimulated and conveyed to brain by cochlear nerve 6. Pressure waves descend and become vibrations again

Question 65

What are the symptoms of CN VII associated with pathology at the internal acoustic meatus?

Answer 65

- ipsilateral loss of facial expression - ipsilateral loss of taste - dry mouth - reduced general sensation in the auricle

Question 66

What are the symptoms of CN VIII associated with pathology at the internal acoustic meatus?

Answer 66

- ipsilateral loss of hearing (cochlear nerve) | - ipsilateral loss of balance (vestibular nerve)