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TBL 35 Flashcards

1
Q

Discuss where the eyeball, optic nerve, and extra ocular muscles are in relation to the orbit.

A

eyeball occupies the anterior portion of the orbit and the optic nerve (CN II) and extraocular muscles are surrounded by white fat in the posterior portion of the orbit.

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2
Q

the MEDIAL orbital walls are (direction) to each other and

the LATERAL orbital walls form (direction) to each other.

A

the medial orbital walls are parallel to each other and

the lateral orbital walls form a right angle to each other.

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3
Q

What bones form the lateral walls of the orbit?

A

the thick zygomatic bones and flat greater wings of the sphenoid bone form the lateral walls of the orbit.

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4
Q

Discuss the ETHMOID bone/cells (forms/contributes).

A

the ethmoid bone mainly forms the medial walls

ethmoid cells occupy the core of the ethmoid bone that also contributes to the lateral walls of the nasal cavity

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5
Q

What forms the floor and roof of the orbit?

The orbital roof is the (structure).

A

maxilla form the floor of the orbit
frontal bone form the roof of the orbit

the orbital roof is the floor of the anterior cranial fossa.

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6
Q

the optic canal in the lesser/greater wing of the SPHENOID bone is (location relation) to the superior/inferior orbital fissure.

Discuss what the inferior orbital fissure demarcates.

A

the optic canal in the lesser wing of the sphenoid bone is just medial to the superior orbital fissure

the inferior orbital fissure demarcates the floor and lateral wall of the orbit.

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7
Q

On the skull, identify portions of the orbital walls formed by the frontal bone, ethmoid bone,
maxilla, zygomatic bone, and greater wing of the sphenoid bone. Distinguish the optic
canal, superior orbital fissure, and inferior orbital fissure.

A

Bone (in lab)

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8
Q

Distinguish the palpebral and bulbar conjunctiva and the

superior and inferior conjunctival sacs and fornices.

A

the palpebral and bulbar conjunctiva and the

superior and inferior conjunctival sacs and fornices.

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9
Q

The palpebral tissue is (location relation) to eyelids.

A

the palpebral fissure between the upper and lower eyelids.

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10
Q

What strengthen the eyelids.

A

bands of dense connective tissue called the tarsus strengthen the eyelids.

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11
Q

Where does the levator palpebral attach to?

Define the superior tarsal muscle and where it attaches.

A

the levator palpebral attaches to the dermis of the superior eyelid.

smooth muscle constituting the distal part of the levator
palpebral is called the superior tarsal muscle that attaches to the tarsus.

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12
Q

Discuss the levator palpebral (fxn most of time and sometimes)

A

the levator palpebral, which is opposed most of the time by gravity, serves as the antagonist of the superior half of the orbicularis oculi.

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13
Q

Discuss location of lacrimal gland and the spread of its secretion.

A

the lacrimal gland is positioned superolaterally in the

orbit and its secretion (lacrimal fluid) spreads across the eyeball to the medial angle of the eye.

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14
Q

Discuss how lacrimal fluid is drained and location.

A

puncta in the medial aspects of the eyelids drain lacrimal fluid into the nasolacrimal duct that empties onto the epithelial surface of the nasal cavity.

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15
Q

VM IMAGE: EYE – MCW 215: Locate the superior and inferior conjunctival sacs and fornices, the tarsus in the upper eyelid, and the orbicularis oculi in the upper and lower eyelids.

A

VM

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16
Q
  1. From Fractures of Orbit, pp. 909: What is a “blowout” fracture of the orbit and why does exophthalmos often result?
A

Indirect trauma that displaces the orbital walls is called a “blowout” fracture of the orbit. Orbital fractures often result in intraorbital bleeding which exerts pressure on the eye ball–> exophthalmos (protusion of the eyeball).

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17
Q
  1. From Orbital Tumors, pp. 909: Why can tumors of the middle cranial fossa cause exophthalmos?
A

Tumors in the middle cranial fossa may pass through the superior orbital issues and into the orbital cavity–> exophthalamos.

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18
Q
  1. From Clinical Point, pp. 450 (EH): What is conjunctivitis?
A

Inflammation of the bulbar or palpebral conjunctiva.

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19
Q

What forms the optic vesicles?

A

bilateral projections from the neuroectoderm of the diencephalon form the vesicles.

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20
Q

What forms the lens placodes?

A

after contacting the surface ectoderm, the distal ends of the optic vesicles invaginate and the surface ectoderm thickens to form the lens placodes.

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21
Q

What forms the single/double- layered optic cups. The optics cups remain attached to (structure and how?).

A

the invagination of the optic vesicles forms the double-layered optic cups that remain attached to the diencephalon by the optic stalks.

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22
Q

What forms the lens vesicles?

A

the lens placodes invaginate to form the lens vesicles.

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23
Q

Define choroid fissure and its function.

A

the choroid fissure, a longitudinal invagination of the optic stalks and optic cups, allows mesenchyme to invade the inside of the optic cups.

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24
Q

Define the role of mesenchyme in relation to the developing lens.

A

the mesenchyme conveys branches of the hyoid artery to the developing lens.

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25
Q

What transpires after (cell) becomes the (describe) vitreous body?

A

after the mesenchyme becomes the transparent gelatinous vitreous body, the arterial branches obliterate and disappear.

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26
Q

What becomes the THIN pigmented layer of the retina?

What forms the THICK neuronal layer of the retina?

A

the outer layer (i.e., furthest from the center) of the optic
cups becomes the thin pigmented layer of the retina

neuronal growth in the inner layer forms the thick neural layer of the retina.

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27
Q

What forms CN II and what does CN II enclose?

A

sensory axons from the neural retina form the optic nerve (CN II) that encloses the hyaloid artery within the choroid fissure of the optic stalk.

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28
Q

What causes the transformation of the optic stalk into the optic nerve? What does the optic nerve enclose?

A

subsequent closure of the choroid fissure transforms

the optic stalk into the optic nerve that encloses the central artery of the retina

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29
Q

What forms the choroid and what forms the sclera?

A

mesenchyme external to the optic cups forms an inner (i.e., closest to pigmented retinal layer) vascularized layer designated the choroid, and an outer fibrous layer called the sclera.

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30
Q

the sclera is continues posterior/anterior with (structures).

A

the sclera is continuous with the dural covering of the

optic nerve posteriorly, and with the cornea anteriorly.

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31
Q

What does the choroid end anteriorly as? (Answer) is continuous with (structure).

A

the choroid ends anteriorly as the ciliary body that is continuous with the iris.

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32
Q

Where does the neural retina end at? Thus…?

A

the neural retina ends at the ciliary body

thus, the ciliary body and iris are covered by a double-layered epithelium formed by an inner nonpigmented layer and the outer pigmented layer of the retina.

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33
Q

What forms the pupils?

A

the pupils are formed by closure of the choroid fissures in the optic cups.

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34
Q

What does the optic disc mark?

A

the optic disc marks the posterior exit of CN II from the

eye.

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35
Q

What vessel supplies the neural retina (describe).

A

the optic nerve encloses the central retinal artery which supplies the neural retina.

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36
Q

Use top right drawing, pp. 448 to ascertain the labeled

arterioles (ignore names) are branches of the ciliary artery

A

ID

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37
Q

What supplies the choroid and sclera?

A

the ciliary artery supplies the choroid and sclera.

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38
Q

Discuss the origins of the ciliary and CENTRAL retinal arteries and the origin of (answer).

A

the hyaloid artery-derived ophthalmic artery

generates both the ciliary and central retinal arteries.

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39
Q

Discuss the receptors and cells contained by the Neural retina and describe the arrangement.

A

the neural retina contains outer photoreceptors (rods

and cones), central bipolar cells, and inner ganglion cells linked by serial synapses.

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40
Q

Light pass though the (layers) before reaching the photoreceptors.

A

light impulses pass through the ganglion and bipolar layers before reaching the photoreceptors.

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41
Q

Discuss the ADJOINING relation of light-sensitive segments and its issue.

A

light-sensitive segments of the photoreceptors adjoin

the retinal pigmented epithelium but lack secure junctional attachments.

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42
Q

Function (application) of rods.

Discuss the ratio of rods to cones.

A

rods produce visual images in shades of gray from dim light perception

rods outnumber the three types of cones, with selective sensitivities to blue, green, and red wavelengths, by 15:1.

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43
Q

Location of fovea centralis and significance of it (describe).

A

the fovea centralis in the posterior aspect of the retina

is the site of highest visual acuity because the ganglion and bipolar cells are compressed to the periphery and the remaining photoreceptors are all cones.

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44
Q

VM IMAGE: EYE – NJMS 011: Locate the optic disc and central retinal artery in the optic nerve. Distinguish the sclera, choroid, retinal pigmented epithelium and neural retina. Find the nuclei of the photoreceptors, bipolar neurons, and ganglion cells and locate the fovea centralis.

A

VM

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45
Q
  1. From Clinical Correlates, pp. 336 (ME): What defect causes Coloboma iridis?
A

The choroid fissure fails to close and a cleft persists only in the IRIS—> Coloboma iridis.

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46
Q
  1. From text, pp. 446 (EH): Why is the optic disc the blind spot of the retina?
A

Lacks photoreceptors and is insensitive to light.

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47
Q
  1. From Clinical Point, pp. 442: What are common causes of retinal detachment?
A

Diabetic retinopathy and intraocular infection.

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48
Q

What holds the lens in a FAIRLY fixed position?

A

the zonular fibers and vitreous body hold the lens in a fairly fixed position.

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49
Q

What and how does the lens thickness change?

A

the smooth muscle of the ciliary body alters lens thickness by regulating tension on the zonular fibers.

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50
Q

Where do the ZONULAR fibers attach to?

A

zonular fibers attach to the lens capsule.

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51
Q

What generates lens fibers (describe answer and lens the fibers).

A

the single layer of lens epithelium inside the capsule generates lens fibers (i.e., elongated, anucleate epithelial cells with distinct cytoplasmic proteins called crystallins).

52
Q

Discuss where the the single layer of lens epithelium resides and (structure) represents the earliest formed lens FIBERS.

A

the epithelium resides only along the anterior surface of the lens and perceive the fetal nucleus represents the earliest formed lens fibers.

53
Q

Discuss the time frame/patter of lens fibers development.

A

successive waves of lens fibers develop from the embryonal nucleus through adulthood.

54
Q

Discuss the layers of cells of the ciliary body and ciliary processes.

A

they are double-layered epithelium of the ciliary body and ciliary processes.

55
Q

Discuss the function of the the NONpigmented layer of the double-layered epithelium of the ciliary body and ciliary processes.

A

the nonpigmented layer secretes aqueous humor (similar to CSF) into the posterior chamber and envision it circulates through the pupillary aperture into the anterior chamber.

56
Q

Discuss the function of the canal of SCHLEMM

A

the canal of Schlemm drains aqueous humor from the anterior chamber into venules of the sclera.

57
Q

Locate and recall the the smooth muscle pupillary dilator and pupillary constrictor in the stroma of the iris.

A

ID

58
Q

What determines eye color?

A

eye color is determined by relative numbers of melanocytes in the stroma.

59
Q

What cell types cover the anterior and posterior surfaces of the cornea?

A

nonkeratinized stratified squamous cover the anterior surface of the cornea

simple squamous epithelia cover the posterior surface of the cornea

60
Q

Discuss the nourishment of the EPITHELIA and Avascular STROMA. Describe the tissue of the Avascular STROMA.

A

the epithelia and avascular stroma (dense connective tissue) are nourished by the aqueous humor.

61
Q

VM IMAGE: EYE – MCW 215: Find the cornea, anterior chamber, iris, pupil, posterior
chamber, and vitreous body. VM IMAGE: EYE – NJMS 011: Distinguish the ciliary body,
ciliary processes, and zonular fibers that suspend the lens.

A

VM

62
Q
  1. From text, pp. 434: Why is the cornea a good candidate for transplantation?
A

Being avascular the cornea is immunologically privileged.

63
Q

Locate the superior and inferior obliques and the superior, inferior, medial, and lateral rectus muscles.

What elevates the upper eyelid (Structure)?

A

levator palpebral elevates the upper eyelid

64
Q

Function of medial rectus and lateral rectus.

A

medial rectus adducts the pupil

lateral rectus abducts the pupil

65
Q

Function of superior oblique and inferior rectus.

A

superior oblique depresses and abducts the pupil

inferior rectus depresses and adducts the pupil (i.e., together the superior oblique and inferior rectus depress the pupil straight downward).

66
Q

Function of inferior oblique and superior rectus.

A

inferior oblique elevates and abducts the pupil

superior rectus elevates and adducts the pupil (i.e., together the inferior oblique and superior rectus elevate the pupil straight upward).

67
Q

Discuss the route of CN III, CN IV, and CN VI to the orbit.

A

the occulomotor nerve (CN III), trochlear nerve (CN IV),

and abducent nerve (CN VI) pass from the middle cranial fossa through the superior orbital fissure into the orbit.

68
Q

What is the mnemonic device for innervation of the extraocular muscles?

A

LR6SO4AO3

69
Q

Discuss the route of the internal carotid artery to the ANTERIOR CLINOID process.

What nerves course ANTERIORLY with the Internal Carotid artery?

A

the internal carotid artery passes between the venous
channels of the dural cavernous sinus as it courses toward the anterior clinoid process.

CNs III, IV, VI, CN V1, and CN V2 course anteriorly with the artery.

70
Q
  1. From Figure 7.56, pp. 902: How are the six extraoccular muscles clinically tested?
A

To isolate the actions of depression/elevation by recti/oblique muscles we move to lateral/medial extremes.

Lateral rectus gets eye to lateral orbit–> only SR/IR work
Medial rectus gets eye to medial orbit–> only IO/SO work

71
Q
  1. From Paralysis of Extraoccular Muscles, pp. 913: How do CN III and CN VI palsies differ? Why is CN IV paralysis characterized by diplopia when looking downward?
A

CN III- eye droops and cannot be raised due to unopposed orbiculares oculi (supplied by facial nerve). Fully dilated and non-reactive (unopposed dilator pupillae), and eye is “down and out”

CN IV- CANNOT ABduct. Full adduct by unopposed medial rectus.

When one attempts to use the paralyzed muscle it will produce two images (diplopia).

72
Q
  1. From Fractures of Cranial Base, pp. 876: How can fractures of the cranial base result in pulsating exophthalmos and which nerves can be affected?
A

Internal carotid may be torn producing an arteriovenous fistula within the cavernous sinus. The arterial blood rushing into the cavernous sinus enlarges it and causes retrograde venous blood into tributaries–> exophthalmos which can follow the radial pulse.

CN 3,4,6, V1,V2

73
Q

Where is the parasympathetic ciliary ganglion located?

What is the origin of the nasociliary nerve?

A

the parasympathetic ciliary ganglion in the posterior
orbit

the nasociliary nerve is an orbital branch of CN V1.

74
Q

Discuss the PREsynaptic parasympathetic fibers of CN III location of synapse. Discuss POSTsynaptic fibers fibers of CN III location of joining and effector muscle.

A

presynaptic parasympathetic fibers of CN III synapse in the ciliary ganglion and postsynaptic fibers join the short ciliary nerve, a branch of nasociliary nerve, for transport to the ciliary muscle and pupillary constrictor.

75
Q

Discuss AFFERENT fibers of the SHORT CILIARY nerve (sensation, coveys from where to what)?

A

afferent fibers of the short ciliary nerve convey somatic sensations to the trigeminal ganglion from the posterior eye.

76
Q

Discuss the long ciliary nerve (origin, type of fibers it transports, type of sensation, its innervation).

A

the long ciliary nerve, another branch of the nasociliary nerve, transports postsynaptic sympathetic fibers to the pupillary dilator muscle and conducts somatic sensations to the trigeminal ganglion from the cornea.

77
Q

Discuss origin of the ophthalmic artery and spatial relation into the OPTIC CANAL.

A

the ophthalmic artery arises from the internal carotid artery at its 180⁰ turn under the anterior clinoid process

the ophthalmic artery enters the orbit adjacent to CN II in the optic canal.

78
Q

Discuss the supraorbital artery (supplies and origin).

A

the supraorbital artery (it supplies the scalp covering the forehead and calvaria) is another orbital branch of the ophthalmic artery.

79
Q

Discuss the route of drainage from the SUPRAORBITAL VEIN to the CAVERNOUS SINUS.

A

the supraorbital vein drains into the superior ophthalmic

vein that traverses the superior orbital fissure and empties into the cavernous sinus.

80
Q

Discuss route of drainage from BRANCHES of the CILIARY VEIN to INFRATEMPORAL FOSSA.

A

branches of the ciliary vein drain into the inferior ophthalmic vein that based on gravity empties mainly into the pterygoid venous plexus in the infratemporal fossa.

81
Q

Discuss the route and drainage of the CENTRAL RETINAL VEIN.

A

the central retinal vein traverses the optic canal and drains into the cavernous sinus.

82
Q
  1. From Pupillary Light Reflex and Corneal Reflex, pp. 911 and 912: Which nerve injuries result in loss of the pupillary reflex and the corneal reflex, respectively?
A 
Pupulliary reflex- afferent limb CN II, efferent limb CN III
Corneal reflex (must touch cornea)- CN V1 and/or CN VII
83
Q
  1. From Horner Syndrome, pp. 913: Why do pupillary constriction and ptosis occur with Horner’s Syndrome?
A

Horner syndrome results from interruption of cervical sympathetic trunk and is manifested by the absence of sympathetically stimulated functions on the ipsilateral side of head.

Constriction- because parasympathetic ally stimulated sphincter of pupil goes unopposed.

Ptosis- because no sympathetic innervation to the superior muscle tarsal muscle

84
Q
  1. From Blockage of Central Artery of Retina and Blockage of Central Vein of Retina, pp. 913:
    How is blindness caused by thrombi in the ophthalmic artery and the cavernous sinus, respectively?
A

Terminal branches of the central artery of the retina are end arteries thus obstruction leads to instant and total blindness.

The cavernous sinus can have the thrombus embolize to the central retinal vein producing a blockage of the small retinal veins–> slow, painless loss of vision.

85
Q

What constitutes the external ear?

A

the helix, antihelix, lobule (lobe), and tragus of the auricle that with the external auditory meatus constitute the external ear.

86
Q

What forms the external auditory meatus?

A

invagination of the ectoderm covering the 1st pharyngeal cleft forms the external auditory meatus

87
Q

Where does the MEATUS terminate (structure and it separates?).

A

the meatus terminates at the tympanic membrane that separates the external ear from the middle ear.

88
Q

What forms the auditory tube which opens into the (structure).

A

endoderm of the 1st pharyngeal pouch forms the

auditory tube that opens into the nasopharynx.

89
Q

How is the tympanic cavity of the middle ear formed? Discuss the chain formation (of structures).

A

tympanic cavity of the middle ear is formed by expansion of the distal portion of the auditory tube, and three bony ossicles form a chain across the air-filled cavity.

90
Q

Where does the tympanic cavity reside?

A

the tympanic cavity resides in the petrous temporal bone.

91
Q

What forms the lateral wall of the tympanic cavity?

Discuss what sensations the CN V3 conveys.

A

the tympanic membrane forms the lateral wall of the
tympanic cavity

the auriculotemporal nerve (CN V3) conveys somatic sensations from the external acoustic meatus including the external surface of the tympanic membrane.

92
Q

Visualize the roof, walls, and floor of the tympanic cavity.

Discuss CN IX and its route to convey ____ sensation.

A

tympanic nerve (CN IX) pierces the floor to convey somatic sensations from the cavity including the internal surface of the tympanic membrane.

93
Q

CN IX exits (route).

A

CN IX exits the posterior cranial fossa via the jugular foramen

94
Q

Discuss what CN IX pierces. What forms (answer)?

A

the tympanic nerve pierces the fissure in the floor of the tympanic cavity, which is formed by the external surface of the petrous temporal bone.

95
Q

What forms the LESSER Petrosal nerve and discuss the route of the lesser petrosal nerve.

A

the tympanic nerve plexus generates the lesser petrosal nerve that pierces a fissure in the roof of the tympanic cavity to enter the middle cranial fossa.

it traverses the foramen ovale to enter the infratemporal fossa and synapse in the otic ganglion.

96
Q

Discuss the route of CN VII.

A

CN VII courses toward the stylomastoid foramen in the facial canal that resides in the medial and posterior walls of the tympanic cavity.

97
Q

Where and what generates the chorda tympani? Discuss the route of the chorda tympani.

A

in the facial canal, CN VII generates the chorda tympani that crosses the medial surface of the malleus bone enroute to another fissure in the floor of the tympanic cavity for entrance into the infratemporal fossa.

98
Q

The malleus inserts into (portion and structure).

A

the malleus inserts into the superior portion of the tympanic membrane

99
Q

The malleus articulates with (structure) that articulates with (structure), which inserts into (structure).

A

the malleus articulates with incus that articulates with the

stapes, which inserts into the membranous oval window.

100
Q

What creates the boundary between the tympanic cavity and inner ear?

A

the oval window covers an oval opening in the medial wall of the tympanic cavity thus creating a boundary between the tympanic cavity and inner ear

101
Q

Define the structural function of the auditory tube (AKA).

A

the auditory (pharyngotympanic) tube unites the tympanic cavity with the nasopharynx.

102
Q

Use function of the pharyngotympanic tube, pp. 970 to describe how the levator palatine and tensor palatine muscles contribute to the function of the auditory tube.

A

a

103
Q
  1. From Otitis Media and Perforation of Tympanic Membrane, pp. 978-979: What are the
    causes and symptoms of otitis media? How is a myringotomy performed to relieve the
    symptoms and if improperly performed, which nerve can be injured?
A

Often secondary to upper respiratory infections.

Sx- earache, ear popping, if unTx- impaired hearing.

Myringotomy is made postero-inferiorly through the tympanic membrane. Chorda tympani nerve may be injured.

104
Q
  1. From Blockage of Pharyngotympanic Tube, pp. 979: How does blockage of the auditory tube affect hearing?
A

When the pharyngotympanic tube is blocked, residual air is absorbed into the mucosal blood vessels, resulting in lower pressure in the tympanic cavity, retraction of the tympanic membrane, and interference with its free movement—> finally hearing is affected.

105
Q

Locate the otic vesicle on the surface ectoderm of the hindbrain

A

ID

106
Q

Discuss what occurs with the ____ vesicle in relation to the surface ectoderm.

A

the otic vesicle invaginates and separates from the surface ectoderm.

107
Q

What forms the MEMBRANOUS labyrinth of the inner ear?

A

the membranous labyrinth of the inner ear is formed by the separated otic vesicle.

108
Q

The MEMBRANOUS Labyrinth is embedded within (structure). How is (part of answer) formed?

A

membranous labyrinth is embedded within the bony labyrinth of the inner ear that is formed by interconnected cavities in the petrous temporal bone.

109
Q

Discuss what the vestibule of the bony labyrinth contains.

Discuss what the OUTPOCKETING from the utricle form.

A

vestibule of the bony labyrinth contains the saccule and utricle of the membranous labyrinth

outpocketings from the utricle form three semicircular ducts that fill the semicircular canals of the bony labyrinth.

110
Q

Discuss the spatial arrangement of the cochlear duct to form ____ turns.

A

the cochlear duct extends from the saccule into the cochlea of the bony labyrinth where it spirals to form 2.5 turns.

111
Q

CSF-like fluid fills both the (structures).

A

CSF-like fluid fills both the membranous and bony labyrinths.

112
Q

Use Figure 7.117 (C), pp. 974 to locate the cochlear duct in the shell-shaped cochlea and the
semicircular ducts extending from the utricle into the semicircular canals.

A

ID

113
Q

pp 974 Use Figure 7.117 (D) toobserve one end of each semicircular duct contains sensory epithelium (purple dots) and the red dots denote the sensory epithelia of the utricle and saccule.

A

Image

114
Q

PERIPHERAL projecting fibers from the ______ neurons of the VESTIBULAR ganglion synapse with the (structures).

A

peripheral projecting fibers from the bipolar neurons of

the vestibular ganglion synapse with the sensory epithelia of the utricle and saccule.

115
Q

Discuss the differences of activation caused by angular acceleration and linear acceleration.

A 
angular acceleration (spinning motion) activates the sensory cells of the semicircular ducts and linear
acceleration activates the sensory epithelia of the utricle and saccule.
116
Q

What forms the vestibular division of CN VIII?

A

central projecting fibers from the vestibular ganglion form the vestibular division of CN VIII.

117
Q

Discuss the spiral cochlear duct (what it contains and serves as physically).

A

the spiral cochlear duct, which contains the spiral organ,
partitions the cochlea into the scala vestibuli and scala tympani that communicate at the apex of the cochlear spiral via the helicotrema.

118
Q

What forms the cochlear division of CN VIII.

A

peripheral fibers from the bipolar neurons of the spiral ganglion synapse with sensory epithelial cells of the spiral organ and central projecting fibers from the ganglion form the cochlear division of CN VIII.

119
Q

Discuss the route of CN VIII to enter the brainstem.

A

CN VIII traverses the internal acoustic meatus of the petrous temporal bone to enter the brainstem.

120
Q

On the skull, identify the internal acoustic meatus in the petrous part of the temporal bone.

A

Bone (in Lab)

121
Q

Discuss what sounds waves do to the tympanic membrane and what is transmitted and where?

A

sound waves vibrate the tympanic membrane and the

ossicles transmit the vibrations to the oval window.

122
Q

Discuss what occurs when there is vibration of the oval window.

A

vibration of the oval window creates hydraulic pressure waves in the fluid-filled scala vestibuli and scala tympani that move the spiral organ and activate its sensory cells.

123
Q

Discuss pressure waves inside the tympanic cavity.

A

the pressure waves are dissipated into the air of

the tympanic cavity by the round window.

124
Q

What occurs during exposure to loud sounds?

A

During exposure to loud sounds contraction of the tensor tympani and stapedius, which attach to the malleus and
stapes respectively, dampens the oscillatory range of the tympanic membrane and oval window to protect the inner ear.

125
Q

VM IMAGE: INTERNAL EAR – NJMS 012: Locate the cochlea in the superior portion of the
image. Select one cross-section of the triangle-shaped cochlear duct and identify the spiral
organ. Note the continuity of the scala vestibuli and scala tympani and at the helicotrema. Find
a section of the utricle with a contiguous semicircular duct at the right side of the image.

A

VM

126
Q
  1. From Muscles Associated with Auditory Ossicles, pp. 972-973: Why do the tensor tympani
    and stapedius have different innervations?
A

Tensory tympani is supplied by CN V3 and stapedius by CN VII.

127
Q
  1. From Clinical Point, pp. 461 (EH): How do histologic changes characteristic of Meniere’s
    disease predict its symptoms?
A

Characteristic distention and distortion of the membranous labyrinth may lead to degeneration of receptor hair cells in both vestibule and cochlea.

Nervous System (3 decks)

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