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MBBS2/Anatomy~HEAD & NECK > The ear > Flashcards

The ear Flashcards

(118 cards)

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1
Q

the ear is divided into what 3 parts

A
  1. external
  2. middle
  3. inner
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2
Q

what are the functions of the ear

A

-hearing
-balancing/ equilibrium

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3
Q

what does the external ear comprise of

A

-auricle
-external acoustic meatus

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4
Q

what does the auricle do

A

collect sound

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5
Q

what does the external acoustic meatus do

A

conduct sound to the tympanic membrane

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6
Q

what is the auricle made of

A

elastic cartilage ( and covered by skin)

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7
Q

what depressions does the auricle have

A

-concha
-helix
-antihelix
-tragus
-antitragus
-lobule

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8
Q

what is the lobule of the auricle made of

A

fibrous tissue, fat and blood. It has no cartilage

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9
Q

what is the function of the outer ear

A

-collects sound
-localization
-resonator
-protection
-sensitive

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10
Q

what is the arterial supply of the auricle

A

-posterior auricular artery
-superficial temporal artery

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11
Q

whats the nerve supply of the auricle

A
  • on the lateral surface is the great auricular nerve
    -on the skin superior to the external acoustic meatus is the auriculotemporal nerve, which is a branch of the mandibular division of the trigeminal nerve
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12
Q

what is the lymphatic drainage of the auricle

A

-superficial parotid lymph nodes
-mastoid lymph nodes
-superficial cervical lymph nodes

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13
Q

what is the structure of the external acoustic meatus

A

-outer 1/3 is cartilaginous and covered by skin
-the inner 2/3 is bony and covered by thin skin which is continuous with the external layer of the tympanic membrane
-it has ceruminous and sebaceous glands in outer half which produce cerumen (ear wax)
-has a tortuous downward and forwards course

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14
Q

whats the nerve supply of the external acoustic meatus

A

-auriculotemporal branch from the trigeminal nerve
-the auricular branch from the vagus nerve

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15
Q

what does the tympanic membrane do

A

-separates the external ear and middle ear
- vibrates against malleus in the middle ear

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16
Q

how does the tympanic membrane appear through the otoscope

A

-has concavity towards the external acoustic meatus
-has a shallow cone like depression at the center called the umbo
-has a cone of light which radiates anteroinferiorly from the umbo

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17
Q

what are the subdivision of the tympanic membrane

A

-pars flaccida
-pars tensa

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18
Q

what are the surfaces of the tympanic membrane like

A

lateral surface- is concave
medial surface- is convex (at umbo)

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19
Q

between the fibrous and mucous layer of the tympanic membrane what is there

A

-handle of malleus
-chorda tympanic nerve (which crosses medially)

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20
Q

what are the layers of the tympanic membrane

A
  1. outer cuticular layer- composed of keratinized hairless and devoid of dermal papillae ( a thin layer of skin)
  2. intermediate fibrous layer- composed of outer radiating and inner circular fibers of type I & II collagen
  3. inner mucous layer- composed of simple columnar/squamous cells
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21
Q

whats the nerve supply of the tympanic membrane

A

-the auriculotemporal branch of the mandibular division of the trigeminal nerve which supplies the anterior half of the lateral surface

-the auricular branch(Arnolds nerve) of the vagus nerve which supplies the posterior half of the lateral surface

-the tympanic branch (Jacobson’s nerve) of the glossopharyngeal nerve which supplies the medial surface

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22
Q

whats the nerve supply of the tympanic membrane

A

-the auriculotemporal branch of the mandibular division of the trigeminal nerve which supplies the anterior half of the lateral surface

-the auricular branch(Arnolds nerve) of the vagus nerve which supplies the posterior half of the lateral surface

-the tympanic branch (Jacobson’s nerve) of the glossopharyngeal nerve which supplies the medial surface

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23
Q

what muscles inhibit vibration when sound is too loud

A

-tensor tympanic muscle which inserts on malleus (dampens vibrations of the tympanic membrane)
-stapedius muscles which inserts on stapes (dampens vibrations of the stapes)

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24
Q

where does the middle ear lie

A

in the petrous part of the temporal bone

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25
what does the middle ear consist of
-tympanic cavity and mucous membrane -epitympanic recess
26
the middle ear is connected to what
nasopharynx by the eustachian tube mastoid air cells by the mastoid antrum
27
pneumatization from the nasopharynx/ retrograde infection from pharynx can cause what
-otitis media -mastoiditis
28
the middle ear gets its sensory innervation from what
glossopharyngeal nerve
29
what auditory ossicles does the middle ear contain
malleus incus ad stapes which are joined by the synovial joints
30
what can affect the synovial joints of the auditory ossicles
-ankylosis -otosclerosis
31
what muscles are found in the middle ear what innervates them and what do they do
stapedius muscle ( VII) and tensor tympani (V3), which dampen sounds and protect inner ear
32
what nerves does the middle ear contain
-the chorda tympani a branch of CN VII -the tympanic plexus of nerves
33
what are the walls of the middle ear and what are their components
roof/ tegmental wall - has the tegmen tympani which is a thin plate of bone that separates the tympanic cavity from the dura in the floor of the middle cranial fossa floor/ jugular wall - has a layer of bone that separates the cavity from the superior bulb of the internal jugular vein lateral/ membranous wall- has the tympanic membrane with epitympanic recess superiorly medial wall/ labyrinthine wall - separates the tympanic cavity from the inner ear anterior wall /carotid -separates the tympanic cavity from the carotid canal and superiorly lies above opening of eustachian tube and canal of tensor tympani posterior wall -is connected by aditus to mastoid antrum and air cells
34
what is the mastoid antrum
a cavity in the mastoid process of the temporal bone
35
what does the aditus (opening to the mastoid antrum) do
connect the mastoid antrum to the epitympanic recess
36
what does the tegmen tympani do
separates the mastoid antrum from the middle cranial fossa
37
what does the floor of the mastoid antrum do
communicate with the mastoid air cells via several openings
38
what lines the mastoid antrum and air cells
mucosa
39
what is the mastoid antrum related to anteroinferiorly
facial nerve canal
40
what does the auditory tube do
connect tympanic cavity to nasopharynx and equalizes the air pressure between the middle ear and atmosphere
41
what is the structure of the auditory tube
the posterior third is bony and the rest is cartilaginous
42
what is the mucosa of the auditory tube continuous with
the tympanic cavity and nasopharynx
43
what is the nerve supply of the auditory the
tympanic plexus
44
what can open the auditory tube
contraction of the levator veli palati ,tensor veli palati, tensor tympani and salpingopharyngeus through swallowing, yawning and chewing
45
what are the auditory ossicles attached to
malleus- tympanic membrane incus- connects malleus to stapes stapes- oval window
46
what covers the auditory ossicles
mucous membrane lining the tympanic cavity
47
what is the function of the auditory ossicles
to transmit vibrations from the tympanic membrane to the oval window
48
what are the functions of the ligaments of the middle ear
-restrict and confine the effect of ossicles to act as a lever -restrict movements to reduce the chance of damage to the inner ear -prevent distortion to sound
49
what is the acoustic reflex
its when the stapedius and tensor tympani muscle contract in response to loud sounds, therefore reducing the transmission of sound to the inner ear
50
what makes up the inner ear
-cochlea -vestibule -semicircular canals
51
what is the cochlea for
hearing
52
what is the vestibule for
static equilibrium
53
what is the semicircular canal for
dynamic equilibrium
54
where does the internal ear lie
petrous part of temporal bone
55
what does the internal ear contain
the vestibulocochlea organ
56
what is the function of the internal ear
sound reception and balancing
57
what does the internal ear consist of
-bony labyrinth -membranous labyrinth ( has sacs and ducts that contain endolymph)
58
what separates the bony labyrinth and the membranous labyrinth
perilymph
59
what is the bony labyrinth
its a fluid filled space surrounded by the otic capsule which is a dense bone
60
the bony labyrinth is composed of what
-bony cochlea -bony vestibule -bony semi-circular canals
61
what is the bony cochlea
its a shell shaped bony labyrinth that contains the cochlea duct
62
where does the spiral canal of the cochlea begin
at the vestibule and then winds around the modiolus (a bony core)
63
what does the modiolus contain
the cochlea nerve and blood vessels
64
what does the bony labyrinth communicate with
1. subarachnoid space- through the cochlear aqueduct 2. middle ear- through the round window closed by the secondary tympanic membrane
65
what is the bony vestibule
a small oval chamber that contains components of the balance system
66
what components of the balance system does the bony vestibule contain
-utricle -saccule
67
what is the bony vestibule continuous with
1. bony cochlea anteriorly 2. bony semi circular canal posteriorly 3. posterior cranial fossa through the aqueduct of vestibule
68
what is the course of the aqueduct of vestibule
it extends to the posterior surface of the petrous part of the temporal bone to open in the internal acoustic meatus
69
what does the aqueduct of vestibule contain
the endolymphatic ducts and blood vessels
70
what are the 3 canals of the bony semi-circular canal
1. anterior 2. posterior 3. lateral
71
how do the 3 canals of the bony semi circular canals lie
perpendicular to each other
72
what do the 3 canals of the bony semi circular canals communicate with
the bony vestibule posterosuperiorly
73
at the end of each bony semi circular canal is what
the ampulla
74
what do the 3 canals of the semi circular canal contain
semi circular ducts
75
what does the membranous labyrinth consist of
ducts and sacs that communicate with each other other in the bony labyrinth
76
what does the membranous labyrinth contain
endolymph
77
what are the 2 divisions of the membranous labyrinth
1. the membranous cochlear labyrinth 2. the membranous vestibular labyrinth
78
what are the 3 components of the membranous vestibule labyrinth
1. utricle and saccule (otolith organs) 2. 3 semi-circular ducts ( superior, horizontal and posterior) 3. the endolymphatic duct
79
the utricle and saccule communicate through what
utriculosaccular duct
80
what arises from the utriculosaccular duct
endolymphatic duct
81
what does the saccule communicate with
cochlea through the ductus reuniens
82
the utricle and saccule contain receptors where and for what
they have receptors in the macula which respond to linear acceleration and static pull of gravity
83
where do the 3 semi-circular ducts open into
the utricle through 5 openings
84
the semi-circular ducts contain receptors for what and where
they have hair cell receptors in the ampullary crest that respond to rotational acceleration in 3 different planes
85
the semi-circular ducts stimulate what
sensory neurons whose cell bodies are in the vestibular ganglion
86
what controls equilibrium
the vestibular apparatus i.e. the saccule and utricle of the vestibule and the 3 semi circular canals
87
what is static equilibrium
a state of balance relative to the force of gravity
88
what is dynamic equilibrium
its the maintenance of balance during sudden movements
89
what controls static equilibrium
sensory hair cells within the macula of the utricle and saccule
90
in static equilibrium what happens when head position is changed
the otolith membrane that has dense calcium carbonate crystals (otoliths) will respond to gravity. this movement will open transduction channels in the hair cells, producing local potentials which summate to form a nerve AP
91
what is in the ampulla of the semicircular canals
the crista ampullaris which contains hair cells and supporting cells
92
what covers the crista ampullaris
a gelatinous mass called the cupula
93
the neurological connection between eyes and semi circular canals is for what
tracking
94
what is the course of the endolymphatic duct
it transverses the vestibular aqueduct and emerges in the posterior cranial fossa
95
where does the endolymphatic duct open into
the endolymphatic sac that is under the dura mater
96
the endolymphatic duct is a reservoir for what
endolymph formed by blood capillaries
97
.the membranous cochlear labyrinth is composed of what 3 chambers
1. the cochlear duct/ scala media 2. scala vestibuli 3. scala tympani
98
what does the cochlear duct contain
endolymph
99
where does the scala vestibuli begin
oval window
100
where does scala tympani end
round window
101
what does scala vestibuli and scala tympani contain
perilymph
102
where does the scala vestibuli and scala tympani meet
helicotrema
103
where is the cochlear duct suspended between
the spiral ligament on the external wall of the cochlear canal and the osseous spiral lamina of the modiolus
104
what are the boundaries of the cochlear duct
roof- formed by the vestibular membrane floor- formed by the basilar membrane + outer edge of osseus spiral lamina
105
in the cochlear labyrinth whats the receptor of auditory stimuli
the spiral organ of corti
106
what covers the spiral organ of corti
gelatinous tectorial membrane
107
what does the spiral organ of corti contain
hair cells (tips of which are embedded in the tectorial membrane) and their supporting cells
108
movement of hair cells in contact with the tectorial membrane do what
they transduce mechanical vibrations into electrical signals which generate nerve impulses along the cochlear branch of CN VIII
109
cell bodies of sensory neurons are located where
in the spiral ganglia
110
whats the pathway for nerve impulses from the inner ear
the nerves follow the CN VIII en route to the medulla, pons, midbrain and thalamus then to the primary auditory cortex in the temporal lobe
111
what do slight differences in the timing of nerve impulses arriving from the the 2 ears at the superior olivary nuclei in the pons do
it allows us to locate the source of a sound
112
what do outer hair cells of the organ of corti do
they amplify mechanical input to the the inner hair cells
113
what do inner hair cells in the organ of corti do
they send information to the brain
114
what is a summary of how we hear
-sound waves are channeled into the ear canal by the pinna -the sound waves hit the tympanic membrane and cause it to vibrate -this changes the sound waves into mechanical energy -the malleus which is attached to the tympanic membrane starts the ossicles into motion -the stapes then moves in and out of the oval window of the cochlea and creates a fluid motion/ hydraulic energy -the fluid movement causes membranes in the organ of corti to shear against the hair cells, which creates an electrical signal that is sent up the cochlear nerve to the brain and the brain interprets it as sound
115
otoscopic examination is for what
the external acoustic meatus
116
the external acoustic meatus can be examined for what conditions
otitis externa- which is inflammation of the auricle and external acoustic meatus perforation of the tympanic membrane- due to otitis media otitis media- which is when a bulging red tympanic membrane indicates pus in middle ear + blockage of the auditory tube mastoiditis- which is an infection of the mastoid antrum earache- which is a symptom of the otitis externa of media
117
what are middle ear disorders
acute otitis media otosclerosis disarticulation mastoiditis tympanosclerosis OME TM perforation TM retraction cholesteatoma
118
middle ear disorders can be found in people with what
-down syndrome -treacher collins syndrome -BOR syndrome

MBBS2/Anatomy~HEAD & NECK (4 decks)

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