Clinical Anatomy of the Ear Flashcards
1
Q
where is the mastoid process in relation to the external acoustic meatus?
A
mastoid process is posterior to ear
2
Q
which nerves does the temporal bone contain?
A
the facial and vestibulocochlear nerves
3
Q
what is the Pterion?
A
- H-shaped suture where frontal, parietal, temporal and sphenoid meet, it is the thinnest part of the skull
4
Q
what are the 2 parts of the temporal bone?
A
squamous part and petrous part
5
Q
which bones make up the anterior cranial fossa?
A
frontal, ethmoid and sphenoid
6
Q
which bones make up the middle cranial fossa?
A
sphenoid and temporal
7
Q
which bones make up the posterior cranial fossa?
A
temporal and occipital
8
Q
through which base of skull foramen does CN I pass through?
A
cribriform plate of ethmoid
9
Q
foramen for CN II?
A
optic canal
10
Q
foramen for CN III?
A
superior orbital fissure
11
Q
foramen for CN IV?
A
superior orbital fissure
12
Q
foramen for CN V1?
A
superior orbital fissure
13
Q
foramen for CN V2?
A
foramen rotundum
14
Q
foramen for CN V3?
A
foramen ovale
15
Q
foramen for CN VI?
A
superior orbital fissure
16
Q
foramen for CN VII?
A
internal acoustic meatus
17
Q
foramen for CN VIII?
A
internal acoustic meatus
18
Q
foramen for CN IX?
A
jugular foramen
19
Q
foramen for CN X?
A
jugular foramen
20
Q
foramen for CN XI?
A
jugular foramen
21
Q
foramen for CN XII?
A
hypoglossal canal
22
Q
function of external ear?
A
collects and conveys sounds waves to tympanic membrane
23
Q
function of middle ear?
A
amplifies and conducts sound waves to the internal ear
24
Q
what is the oval window?
A
opening into internal acoustic meatus (internal ear)
25
what does the internal ear convert special sensory information into?
into fluid waves then action potentials
26
what makes the skeleton of the external ear?
temporal bone
27
what type of cartilage is in the ear?
elastic
28
what produces earwax in the external ear?
ceruminous glands
29
what is the helix?
outer rim of the ear anteriorly
30
general sensory supply to the helix of the ear?
anterior rami of C2 and C3 spinal nerves
31
what is the general sensory supply to the superior parts of EAM and most of the tympanic membrane ?
CN V3
32
where in the outer ear does vagus nerve supply general sensory innervation to?
inferior parts of EAM and some of tympanic membrane
33
what is the other sensory nerve to the EAM which supplies immediately posterior to the tragus?
the facial nerve
34
where does lymph from the lateral surface of superior half of the auricle drain to?
parotid lymph nodes
35
where does lymph from the cranial surface of superior half of the auricle drain to?
mastoid lymph nodes and deep cervical
36
where does the rest of the auricle (not superior aspect) drain to?
superficial cervical lymph nodes
37
where does lymph from the auricle all eventually drain to?
- deep cervical lymph nodes
- thoracic duct or right lymphatic duct
- venous angle
38
what is the thin part of the tympanic membrane called?
the pars flaccida
39
what is the EAM like in the child?
short and straight
40
in a child how do you pull the auricle to examination the EAM?
gently pull auricle posteroinferiorly
41
what is the EAM like in adults and how do you examine it?
curved, gently pull auricle posterosuperiorly
42
what is the name given to the most inwardly depressed part of the tympanic membrane?
the umbo
43
what name is given to the thick part of the tympanic membrane?
the pars tensa
44
general sensory supply to the external surface of the tympanic membrane?
mostly auriculotemporal branch of CN V3
45
general sensory supply to internal surface of tympanic membrane?
CN IX
46
function of eustachian tube?
connects the tympanic cavity of inner ear to the lateral wall of nasopharynx
47
other names for eustachian tube?
auditory tube or pharyngotympanic tube
48
why can tonsillitis mimic earache?
due to common sensory nerve supply by CN IX
49
what are the auditory ossicles?
the 3 bones of the middle ear
- incus
- malleus
- stapes
50
how to the auditory ossicles articulate?
via synovial joints
51
the handle of the malleus is adherent to the internal aspect of the tympanic membrane, what does this create?
the umbo
52
where is the tympanic cavity in relation to the tympanic membane?
tympanic cavity is posterior to tympanic membrane
53
where is the epitympanic recess?
superior to the tympanic membrane
54
what does the base (footplate) of the stapes fit into?
the oval window- the way into the internal ear
55
what is the aditus?
the doorway into the mastoid antrum from the epitympanic recess
56
what is mastoditis due to?
spread of infection from middle ear through the aditus
57
the facial nerves connection to the CNS?
brainstem at junction between pons and medulla
58
intracranial part of course of facial nerve?
directly into internal acoustic meatus in the posterior cranial fossa
59
base of skull foramen part of course?
internal acoustic meatus and stylomastoid foramen
60
special sensory supply to anterior 2/3rds of tongue?
the chorda tympani branch of facial nerve
61
which salivary glands does the chorda tympani supply with parasympathetic innervation?
submandibular and sublingual
62
what is the tiniest skeletal muscle in the body?
the stapedius
63
what is the function of the stapedius muscle?
reduces stapes movement to protect internal ear from excessive noise
64
in which part of the temporal bone is the facial canal?
the petrous part
65
what does the facial canal connect the internal acoustic meatus to?
the stylomastoid foramen
66
what does the chorda tympani branch of facial nerve connect to after leaving the stylomastoid foramen?
the lingual nerve branch of CN V3
67
what are the muscles of facial expression?
- frontalis
- orbicularis oculi
- elevators of lips
- orbicularis oris
68
how can you clinically assess the muscles of facial expression and motor function of CN VII?
ask patient to
- frown
- close eyes tightly
- smile
- puff out cheeks
69
what gives rise to the appearance of 'sunken cheeks' in illness?
loss of buccal fat pad
70
what are the 2 parts of the vestibulocochlear nerve and what is each part responsible for?
- the cochlear nerve (hearing)
| - the vestibular nerve (balance)
71
what bone does the dense otic capsule sit in?
the temporal bone
72
what does the otic capsule contain?
bony labyrinth - fluid (perilymph) filled spaces inside otic capsule
73
what is suspended within perilymph of bony labyrinth?
- membranous labyrinth
- communicating sacs and ducts
- contains endolymph fluid
74
what is the cupula of the cochlea?
the apex of the spiral
75
how many semicircular canals do we have?
3
- anterior
- lateral and
- posterior
76
what is the cochlear duct, what is it filled with?
a long balloon-like structure within the cochlear filled with endolymph
77
which nerve conducts APs to the brainstem from the cochlear duct?
the cochlear nerve
78
what are the semicircular ducts, what do they contain?
inter-linked balloon like structures within the semicircular canals, filled with endolymph
79
which nerve conducts APs to the brainstem from the semicircular ducts?
vestibular nerve
80
what are the 7 steps of sound transmission?
1. sound waves make tympanic membrane vibrate
2. vibrations transmitted through ossicles
3. base of stapes vibrates in oval window
4. vibration of stapes creates pressure 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
7. pressure waves are dampened at the round window
81
symptoms associated with pathology of CN VII?
- ipsilateral loss of facial expression
- ipsilateral loss of taste
- dry mouth
- reduced general sensation in the auricle (immediately posterior to tragus
82
symptoms associated with pathology of CN VIII?
ipsilateral loss of hearing
| ipsilateral loss of balance
