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Neuro Exam 1 > Anatomy of the Ear > Flashcards

Anatomy of the Ear Flashcards

1
Q

3 divisions of the ear

A

External ear: from auricle to TM

Middle ear: from TM to stapes

Inner ear: encased in temporal bone

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2
Q

Contents of middle ear

A

Auditory ossicles (malleus, incus, stapes)

Stapedius and tensor tympani mm

Chorda tympani n. (Branch of facial)

Tympanic plexus of nn

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3
Q

Contents of inner ear

A

Vestibulocochlear organ including cochlea, vestibule, and semicircular canals

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4
Q

The ear has protective mechanisms from loud sounds. For example, the ______ muscle pulls the stapes posteriorly and tilts its base in the oval window, thereby tightening the ____ ligament and reducing oscillatory range. This also prevents excess movement of the stapes.

The _____ m. Pulls the malleus handle medially, tensing the TM and reducing the amplitude of its oscillations, which also protects from loud sounds

A

Stapedius; anular

Tensor tympani

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5
Q

Major structures of external ear

A 
Helix
Antihelix
Tragus
Antitragus
Concha
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6
Q

Blood supply to external ear

A

Superiorly:
Anterior auricular arteries, which branch from superficial temporal a.

Inferiorly:
Posterior auricular a. which branches from the external carotid a. (Also gives off posterior anastomosing arcades)

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7
Q

Shape and length of external auditory meatus and its relation to otoscopic exam

A

2-3 cm in adults

Lateral third is slightly S shaped and cartilaginous

Medial two-thirds is bony so it cannot be manipulated

On otoscopic exam in adults, helix is pulled posterosuperiorly to reduce curvature of external acoustic meatus

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8
Q

Size of TM

A

1 cm in diameter

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9
Q

Describe orientation of TM

A

Concave toward external acoustic meatus with a shallow depression called the umbo

The central axis of the TM passes perpendicular through the umbo, running anterior and inferiorly as it runs laterally — thus it is oriented like a satellite dish positioned to receive signal from the ground in front of and to the side of the head

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10
Q

Superior to the lateral process of the malleus, the TM is thin, called the ____ ______ which lacks radial and circular fibers that are present in the remainder of the membrane — called the ____ _____

A

Pars flaccida

Pars tensa

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11
Q

The external surface of the TM is supplied by the ______ n. with some innervation by a small auricular branch of the ______ n., which may cause a ______ response when irritated

A

Auriculotemporal (branch of V3); vagus; cough

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12
Q

The internal surface of the TM is supplied by what n?

A

Glossopharyngeal n.

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13
Q

What are the 6 walls of the middle ear cavity?

A 
Roof = tegmental wall
Floor = jugular wall

Membranous lateral wall
Labyrinthine medial wall
Mastoid wall = posterior wall
Carotid wall = anterior wall

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14
Q

The tegmental wall (roof of middle ear) is formed from thin plate of bone called ____ ____ which separates the tympanic cavity from dura mater on floor of middle cranial fossa

A

Tegmen tympani

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15
Q

The jugular wall forms the floor of the middle ear, a layer of bone that separates the cavity from the superior bulb of the _______ v.

A

IJV

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16
Q

The membranous lateral wall of the middle ear cavity is formed by the peaked convexity of the TM. Superiorly it is formed by the lateral bony wall of the _____ ______. The handle of the malleus is attached to the TM, and its head extends into the above space.

Other structures associated with lateral wall are the _____ n. on the floor, which goes up to the tympanic plexus on the promontory and merges with it, continuing up as the _______ n. to the otic ganglion.

Also the _____ n. and the ______ canal, which are above the promontory, foot plate of stapes, and round window

A

Epitympanic recess

Tympanic n.; lesser superficial petrosal n.

Facial; lateral horizontal semicircular

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17
Q

The medial wall of the middle ear (labyrinthine wall) separates the tympanic cavity from the inner ear. It features the ______, which is formed by the initial part (basal turn) of the cochlea, as well as the oval and round windows

A

Promontory

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18
Q

The posterior wall (mastoid wall) of the middle ear cavity features an opening in the superior portion called the aditus to the mastoid antrum, connecting the tympanic cavity to the mastoid cells. This serves as a canal for the _____ n. to descend between the posterior wall and antrum, medial to the aditus.

This is also the location of the pyramidal process containing the tendon of the ______ m.

Also in this region is the ______, a branch of the facial nerve that supplies taste sensation to anterior 2/3 of tongue

A

Facial

Stapedius

Chorda tympani

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19
Q

The anterior (carotid) wall of the middle ear cavity separates it from the carotid canal. Superiorly it has the opening of the _______ and the canal for the _______ m.

A

Pharyngotympanic tube; tensor tympani

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20
Q

The ____ is the ossicle that attaches to the TM.

Its head lies in the epitympanic recess and articulates with the ______.

The neck lies against the ________

A

Malleus

Incus

Pars flaccida

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21
Q

The handle of the malleus is embedded in the TM, thus the malleus moves with the membrane. The handle serves as the insertion point for the tendon of what muscle?

A

Tensor tympani m

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22
Q

The _____ is located between the malleus and stapes, articulating with each. Its large body lies in the _____ ______ where it articulates with the malleus.

The inferior end of one of its limbs articulates with the stapes via the _____ process.

The other limb is connected by a ligament to the posterior wall of the tympanic cavity

A

Incus; epitympanic recess

Lenticular

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23
Q

The head of the stapes is directed laterally, as it articulates with the _____

The base (footplate) fits into the ____ ____ on the medial wall of the tympanic cavity

A

Incus

Oval window

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24
Q

Origin and insertion of tensor tympani m

A

Arises from superior surface of cartilaginous part of eustachian tube, greater wing of sphenoid, and petrous part of temporal bone

Inserts on handle of malleus

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25
Q

Action of tensor tympani m.

A

Pulls handle of malleus medially, tensing the TM and reducing amplitude of its oscillation

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26
Q

Innervation of tensor tympani m

A

Mandibular n. (V3)

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27
Q

Location and insertion of stapedius m

A

Located inside pyramidal eminence (hollow cone-shaped prominence on posterior wall of tympanic cavity)

Its tendon enters the tympanic cavity by emerging from a pinpoint foramen in the apex of the eminence and inserts on the neck of the stapes

28
Q

Action of stapedius m.

A

Pulls stapes posteriorly and tilts its base in the oval window, thereby tightening the anular ligament and reducing the oscillatory range; also prevents excess movement of stapes

29
Q

Innervation of stapedius m.

A

Facial n

30
Q

The inner ear is innervated by the vestibulocochlear n., which enters via the internal acoustic meatus where it divides into the vestibular n. and cochlear n. What structures are supplied by the vestibular n.?

A

Vestibular n. enlarges to form vestibular ganglion, which then splits into superior and inferior parts to supply the utricle, saccule, and 3 semicircular ducts

31
Q

The inner ear is innervated by the vestibulocochlear n., which enters via the internal acoustic meatus where it divides into the vestibular n. and cochlear n. What structures are supplied by the cochlear n.?

A

Supplies receptors of organ of corti (in scala media)

32
Q

What artery (in general) supplies the inner ear?

A

Internal auditory a.

33
Q

Blood supply to bony labyrinth of inner ear

A

Anterior tympanic branch of maxillary a.

Petrosal branch of middle meningeal a.

Stylomastoid branch of posterior auricular a.

34
Q

Blood supply to membranous labyrinth of inner ear

A

Labyrinthine a., which is a branch of inferior cerebellar a.

[labyrinthine a. divides into 3 branches: a cochlear branch and 2 vestibular branches]

35
Q

The first segment of the facial n. associated with the temporal bone surrounding the ear is the ______ segment which emerges from the meatal foramen to the internal auditory canal; it gives off the ______ n. before making its first turn.

After its first turn is the ______ segment which passes behind the ossicles.

It then makes another turn, at which point it is the _____ segment, which is what finally passes through the stylomastoid foramen

A

Labyrinthine; superficial petrosal n.

Tympanic

Mastoid

36
Q

The bony labyrinth is the fluid filled space composed of a series of cavities contained within a dense ____ _____ of petrous temporal bone

A

Otic capsule

37
Q

3 components/contents of bony labyrinth

A

Cochlea
Vestibule of bony labyrinth
Semicircular canals

38
Q

The _____ is the hearing apparatus, found in the osseous labyrinth. It features the _______ window

A

Cochlea; round

39
Q

The vestibule of the bony labyrinth contains the _____ and _____. The _____ window is on the lateral wall, occupied by the stapes.

The vestibule is continuous with the bony _____ anteriorly and the _______ posteriorly

A

Utricle; saccule; oval

Cochlea; semicircular canals

40
Q

The semicircular canals include _______, ______, and _______.

They communicate with the ______ of the bony labyrinth; one end of each semicircular canal contains a bony ______

A

Anterior; posterior; lateral

Vestibule; ampulla

41
Q

The membranous labyrinth contains a watery fluid called _______.

It is divided into 2 divisions: the _____ labyrinth and the _____ labyrinth

A

Endolymph

Vestibular; cochlear

42
Q

The ____ ____ is a sensory area of the ampulla contained in each semicircular duct. It does this via sensors that record movement of ______ in the ampulla resulting frmo rotation of the head in the plane of the duct.

A

Crista ampullaris; endolymph

43
Q

Hair cells of the crista ampullaris, like those of the maculae, stimulate primary sensory neurons, whose cell bodies are in the _____ _____

A

Vestibular ganglia

44
Q

_____ = areas of specialized epithelium in the utricle and saccule

A

Maculae

45
Q

The maculae of the ______ is in the floor of this structure, oriented parallel with the base of the cranium

The maculae of the ______ is vertically placed on the medial wall of this structure

A

Utricle

Saccule

46
Q

Describe innervation of hair cells in the maculae of the utricle and saccule

A

Innervated by fibers of vestibular division of vestibulocochlear n.

Primary sensory neurons are in vestibular ganglia, which are in the internal acoustic meatus

47
Q

The semicircular ducts open into the _____ through 5 openings, reflective of the way the surrounding semicircular canals open into the vestibule

A

Utricle

48
Q

The utricle communicates with the saccule through the utriculosaccular duct, from which the ____ duct arises.

A

Endolymphatic

49
Q

The ______ n. innervates the superior and horizontal semicircular canals, as well as the superior portion of the vestibule (utricle)

A

Superior vestibular n.

50
Q

The _____is continuous with the cochlear duct through a uniting duct

A

Saccule

51
Q

The _____ n. innervates the posterior semicircular canal as well as the posterior portion of the vestibule (saccule)

A

Inferior vestibular n.

52
Q

Waves of hydraulic pressure created in ______ of the vestibule by vibrations of the base of the stapes ascend to the apex of the cochlea by way of the scala _______.

Pressure waves then pass through the helicotrema and descend back to the basal turn of the cochlea by the scala _______. Here, the pressure waves again become vibrations, this time of the secondary tympanic membrane in the _____ window, and energy is dissipated in the tympanic cavity.

A

Perilymph; vestibuli

Tympani; round

53
Q

Primary receptor of auditory stimuli

A

Spiral organ of corti

54
Q

The spiral organ of corti is situated on the basilar membrane in _____ _____. It is overlaid by a gelatinous _____ ______, which its hair cells are embedded in

A

Scala media; tectorial membrane

55
Q

The top portions (aka closer to center of spiral) of organ of corti detect ______ frequency sounds

The base (aka nearer to oval window) detects ____ frequency sounds

A

Low

High

56
Q

Trauma to the cartilaginous auricle may lead to what condition

A

Auricular hematoma

57
Q

Describe auricular hematoma and potential complications

A

Localized collection of blood between perichondrium and auricular cartilage, causing distortion of contours of auricle

As the hematoma enlarges, it compromises blood supply to the cartilage. If untreated, fibrosis develops in overlying skin forming a deformed auricle (cauliflower ear)

58
Q

How might a lesion of the facial n. affect perception of auditory stimuli?

A

Lesion of facial nerve may lead to paralysis of stapedius m., meaning that its movement will be uninhibited when vibratory stimuli occur

This leads to excessive acuteness of hearing — intolerance of noise

59
Q

What changes occur with eustachian tube with age?

A

Increases in length and S-shape straightens out slightly, leading to a better angle for drainage

60
Q

Tx options for chronic middle ear infection

A

Myringotomy — incision to release pus from middle ear abscess

May be followed by insertion of tympanostomy or pressure equilization tubes in the incision to enable drainage of effusion and ventilation of pressure

61
Q

Why are myringotomy incisions made posteroinferiorly through the TM?

A

Because superior half of TM is more vascular than inferior half; this also avoids injury to chorda tympani and auditory ossicles

62
Q

Cause of meniere syndrome

A

Excess endolymph production or blockage of endolymphatic duct

63
Q

Symptoms and characteristic signs of meniere syndrome

A 
Recurrent tinnitus
Hearing loss
Vertigo
Pressure sensation in ear
Distortion of sound
Sensitivity to noise

Characteristic sign = ballooning of cochlear duct, utricle, and saccule caused by increase in endolymphatic volume

64
Q

Nerve supply to external ear

A

Facial n. —> majority of helix

Vagus n. and glossopharyngeal n. —> concha

Auriculotmeporal n. (branch of CN V) —> anterosuperior helix

65
Q

Lymphatic drainage from external ear occurs anteriorly to ______ nodes, posteriorly to _____ nodes, and inferiorly to _____ nodes

A

Interparotid; posterior auricular; deep digastric

[teachmeanatomy says lymphatic drainage from outer ear is to preauricular, posterior auricular, and superficial temporal nodes…]

66
Q

Sensory innervation to lateral (outer) surface of TM vs. medial (inner) surface of TM

A

Outer surface innervated by CN V3, VII, and X

Inner surface innervated by CN IX

67
Q

Embryologic origin of epitympanic structures vs. mesotympanic structures

A

Epitympanic structures arise from first branchial arch (malleus, incus)

Mesotympanic structures arise from second branchial arch (stapes)

Neuro Exam 1 (17 decks)

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