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Neuroendocrine Exam 1 > 12. Ear Development (KEIM) > Flashcards

12. Ear Development (KEIM) Flashcards

1
Q

What does the spiral organ differentiate from?

A

Cells of the cochlear duct itself.

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2
Q

Tissues of the Middle Ear Derivatives

external auditory meatus and external TM

tubotympanic recess

tympanic membrane

malleus and incus

stapes

covering the ossicles

A

1st pharyngeal groove, surface ectoderm

1st pharyngeal pouch, endoderm

ectoderm, mesoderm, endoderm from PA1

NCC from PA1

NCC PA2

endodermal epithelium

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3
Q

Tensor Tympani

Insertion

Action

Derived from

A

handle of malleus

dampen sounds

PA1 mesoderm, CN V

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4
Q

Stapedius

Insertion

Action

Derived from?

A

neck of stapes

pulls posteriorly, dampens sounds

PA 2 mesoderm, CN VII

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5
Q

Inner Ear

Derived from?

forms how and when

A

surface ectoderm, 1st part to form

4th wk

otic placode from surface endoderm invaginates to form otic pit which rounds up to form the vesicle which will migrate and become primordium of membranous labyrinth

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6
Q

External Ear

Derived from

Innervated by

A

1st and 2nd PA NCC with mesencymal swellings covered with ectoderm

Great auricular, CN V3, VII, and X

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7
Q

How is the tympanic cavity formed?

A

The first pharyngeal pouch foms the tubotympanic recess, which forms the pharyngotympanic tube (proximally) and the tympanic cavity (distally).

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8
Q

From what structures is the external ear derived?

A

The auricular hillocks surrounding the first pharyngeal groove.

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9
Q

What structure connects the cochlea to the saccule?

A

The ductus reuniens.

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10
Q

What embryological tissue is the otic placode made of?

A

Surface ectoderm.

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11
Q

What is the external auditory meatus derived from?

A

The 1st pharyngeal groove.

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12
Q

What is the tympanic membrane derived from?

A

Three parts:

Ectoderm from the 1st pharyngeal groove.

Mesenchyme from pharyngeal arches 1 and 2.

Endoderm from the tubotympanic recess (1st pharyngeal pouch)

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13
Q

Where does the stapedius insert?

Where does the tensor tympani insert?

A

Tensor tympani inserts onto the handle of the malleus.

Stapedius inserts on the neck of the stapes.

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14
Q

What forms the endolymphatic duct and sac?

What trascription factor regulates this differentiation?

A

A diverticulum from the dorsal utricular part of the otic vesicle.

SOHOL

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15
Q

What are the tensor tympani and stapedius muscles derived from respectively?

A

Tensor tympani: 1st pharyngeal arch mesoderm.

Stapedius: 2nd pharyngeal arch mesoderm.

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16
Q

What is formed by the dorsal part of the otic vesicle?

A

The endolymphatic ducts, the semicircular canals, and the utricles.

17
Q

What does the cochlea differentiate from?

A

The ventral (cochlear) part of the otic vesicle.

18
Q

What is microtia?

A

Small or rudimentary auricle, resulting from supressed mesenchymal proliferation

abnormal migration of NCC and hillocks

19
Q

What is a meatal plug?

A

The proliferated of surface ectoderm between the external auditory meatus and tympanic cavity does not undergo apoptosis.

20
Q

Describe the components of the membranous labyrinth

A

Made of the dorsal utricle and the ventral saccule

21
Q

What are the components of the utricle?

A

endolymphatic duct and sac

semicircular ducts and ampullae (hair cells)

macula of utricle (hair cells)

22
Q

What are the components of the saccule?

A

cochlear duct

ductus reunions

macula of saccule, organ of corti (hair cells)

23
Q

What is the specific function of the hair cells in each of these locations:

Ampullae

Macula (utricle and saccule)

Organ of Corti

A

rotational acceleration

gravity and linear acceleration

sound vibration

Inn: CN VIII, Hair cells do not regenerate, come from surface ectoderm

24
Q

Describe perilymph

Duct?

ion content?

found?

A

duct is patent, can flow from subarachnoid space and inner ear (opportunity for meningitis)

similar to CSF, high Na, low K and protein

found within the bony canal system

25
Q

Describe Endolymph

Produced?

Ion content?

stored?

A

stria vascularis

High K and protein, low Na

stored in endolympatic sac within membranous labyrinth

26
Q

What causes auricular appendages?

A

skin tages/cartialginous components around ear

Abnormal migration of NCC (if cartilage) or surface ectoderm hillocks (if skin)

27
Q

Describe Anotia

A

No outer ear

abnormal migration of NCC, no hillocks form.

inner ear likely uneffected

28
Q

What is a possible complication of prolonged middle ear infection?

A

Can erode into perilymph and get into subarachnoid space and get into meninges

29
Q

The bony labyrinth is made of what?

A

mesenchyme

contains vacuoles (scala vestibuli and tympani full of perilymph)

bony elements ossify and locate within the petrous part of the temporal bone

30
Q

Describe congenital deafness

A

usually genetic

maldevelopment of sound conduction by 1st and 2nd arch issues, Treacher-Collins, PRS, or abnormal malleus and incus; fixation of the stapes

31
Q

Sensorineural Deafness can occur in utero by the following teratogens

A

rubella in 7-8wk causes defect in spiral organ and deafness

CMV-leading cause of sensorneural hearing loss

toxoplasmosis (toxoplasma gandii), Syphilis (treponema pallidum) can also cause hearing deficits

Neuroendocrine Exam 1 (22 decks)

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