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Neuro Test 1 > EMB: Ear Development > Flashcards

EMB: Ear Development Flashcards

1
Q

What week does the ear start to develop?

A

4

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2
Q

What germ layer does the middle + external ear come from?

external: auricle (pinna), external acoustic meatus, tympanic membrane (external layer)

Middle: 3 ossicles, tympanic membrane (internal) + middle ear cavity

A

Pharyngeal arches

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3
Q

What germ layer does the inner ear come from?

-vestibulocochlear organ

A

Surface Ectoderm (develops independently)

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4
Q
A
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5
Q

The auricular hillocks of the external ear are __________ cells.

A

Neural Crest

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6
Q

What is the importance of the neural crest cells in the auricular hillock?

A

The neural crest cells migrate and move to form the weird looking external part of the ear.

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7
Q

What is the innervation of the external ear?

A

Great Auricular N (C2 = C3) and Auriculotemporal N.

(+ a litle vagus and facial)

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8
Q

What causes microtia?

A

NC cells did not migrate appropriately

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9
Q

What causes Skin Tags?

A

Problem with migration of surface ectoderm + NC cells

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10
Q

What does the external auditory meatus come from?

A

First pharyngeal cleft of ectoderm

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11
Q

What does the Auricle come from?

A

1st and 2nd pharyngeal arches (NC)

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12
Q

What fails to happen leading to no ear at all and no external auditory meatus?

A

Auricular hillocks + NC cells did not migrate/form

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13
Q

What causes this?

A

Surface ectoderm cells did not undergo apoptosis, so we still have a metal plug.

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14
Q

In the inner ear, how does this development work, in stages?

A

Otic placode –> Otic pit –> Otic vesicle –> membranous labyrinth

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15
Q

What are the 2 parts of the membranous labyrinth?

A

Utricle (dorsal)

Saccule (ventral)

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16
Q

In the membranous labyrinth, what is the utricle dependent on and its subpart the lateral canal of semicircular duct?

A

Dlx5 + Dlx6

lateral canal –> Otx1

17
Q

What components are in the Utricle part of the membranous labyrinth?

A

Semicircular ducts + utricle

18
Q

In the membranous labyrinth, the saccule part is dependent on?

A

Pax6

19
Q

What are the derivatives of the saccule part of the membranous labyrinth?

A

Cochlear duct (Pax 6) + ductus reunions + saccule + organ of corti (cochlea)

20
Q

The inner ear has hair cells that come from surface ectoderm, what are the 3 parts and function?

A

Ampullae - acceleration

Macula - gravity

Organ of Corti - sound vibration

21
Q

What nerve innervates the inner ear?

A

Vestibulocochlear

22
Q

What are the two parts of the vesitubularcochlear N. and their orgin?

A

Vestibular ganglion = SE + NC

Spiral (cochlear) ganglion = SE

23
Q

Perilymph is from the bone and surrounds the endolymph (endo = in). What does it mimic?

A

CSF

24
Q

What is endolymph similar to?

A

Intracellular fluid

25
Q

Where does perilymph come from?

A

A patent perilymphatic duct –> allows free passage from subarachnoid space (which is why it is smilar to CSF)

26
Q

Where does endolymph come from?

A

Stria vascularis

27
Q

What protects the membranous labyrinth?

A

Bony labyrinth

28
Q

What is the bony labyrinth made of?

A

Mesenchyme (mesoderm)

29
Q

In the bony labyrith, which spaces hold perilymph?

A

Scala vestibuli + scala tympani

30
Q

What space houses the endolymph?

A

Scala media

31
Q

In the middle ear, the 1st pharyngeal cleft (ectoderm) forms _________.

A

External auditoy meatus

32
Q

In the middle ear the 1st pharyngeal pounch (endoderm) forms ________.

A

Tubotympanic recess

33
Q

In the middle ear, the tympanic membrane is formed by?

A

Everything!

Ectoderm, Mesoderm, Endoderm

34
Q

In the middler ear, the ossicles (malleus + incus) are formed from?

A

NC!!! = bone

Malleus = 1st arch

Stapes = 2nd arch

35
Q

What nerve innervates the tensor tympani muscle of the ear?

A

CN V

*Anything innervated by 5 = 1st arch*

36
Q

What innervates the stapedius M. of the ear?

A

CN VII

37
Q

The tensor tympani comes from the _________.

A

1st pharngeal arch mesoderm

38
Q

The stapedius M. comes from the _________.

A

2nd pharyngeal arch mesoderm

39
Q

What causes congenital deafness?

A

genetic

Maldevelopment of sound-conduction apparatus of middle + external ears (which come from pharyngeal arches).

Could be due to: first arch syndrome, mallus/incus abnormalities, stapes doesn’t move, hair cells didn’t form, etc.

and

*rubella infection during 7-8th week can cause defects of spiral organ and deafness*

Neuro Test 1 (21 decks)

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