Ear Development Flashcards

1
Q

What structures are a part of the external ear?

A

Auricle (pinna), external acoustic meatus, external layer of tympanic membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What structures are a part of the middle ear?

A

The three ossicles, the internal layer of the tympanic membrane, middle ear cavity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What structures are a part of the inner ear?

A

Vestibulocochlear organ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the auricle derived from?

A

1st and 2nd pharyngeal arches. Auricular hillocks (NCC) covered in surface ectoderm. Migrate and proliferate to make shape of outer ear

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are auricular appendages/skin tags?

A

Hillocks did not migrate properly, may or may not contain cartilage (NCC)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is anotia?

A

No external ear due to abnormal migration/proliferation of NCC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is microtia?

A

Small external ear, due to abnormal migration/proliferation of NCC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the meatal plug?

A

Comes from the 1st pharyngeal cleft/groove. Migrates in to meet up with the pouch, proliferation of surface ectoderm. Supposed to undergo apoptosis to create external auditory meatus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

When does the inner ear form? What is it derived from?

A

Week 4, surface ectoderm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does the inner ear form?

A

Thickening of surface ectoderm makes the otic placode which invaginates to make the otic pit. The pit rounds up to make the otic vesicle which migrates deeper into the head.
Gives rise to the primordium of the membranous labyrinth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What layer does the membranous labyrinth come from?

A

Surface ectoderm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the membranous labyrinth divided into?

A

The utricle (dorsal) and saccule (ventral)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does the utricle give rise to?

A

Endolymphatic duct/sac, semicircular ducts and ampullae, and macula of utricle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does the saccule give rise to?

A

Cochlear duct, ductus reunions, macula of saccule, organ of corti

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What parts of the membranous labyrinth contain hair cells?

A

ampullae of semicircular ducts, macula of utricle, macula of saccule, organ of corti

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does the ampullae detect?

A

Rotational acceleration

17
Q

What does the macula detect?

A

Gravity and linear acceleration

18
Q

What does the organ of corti detect?

A

Sound vibration

19
Q

What layer do the hair cells come from?

A

Surface ectoderm

20
Q

What innervates the inner ear? What layer did it come from?

A

Vestibulocochlear nerve (CN VIII), surface ectoderm

21
Q

What nerve do the cells of the spiral ganglion of the cochlea form?

A

Cochlear N

22
Q

What nerve do the cells of the vestibular ganglion of the cochlea form?

A

Vestibular N

23
Q

What is perilymph?

A

Similar to CSF (high NA, low K and protein), comes from periosteum

24
Q

What is endolymph?

A

Similar to intracellular fluid (high K and protein, low NA), comes from stria vascularis, stored in endolymphatic sac

25
Q

What fills the structures (ducts) of the membranous labyrinth?

A

Endolymph

26
Q

What fills the space (canals) between the membranous labyrinth and the bone?

A

Perilymph

27
Q

How can a chronic middle ear infection get dangerous?

A

If the infection erodes into the perilymph it can get into the subarachnoid space through the perilymphatic duct

28
Q

Where is the bony labyrinth located? What layer is it from?

A

Petrous part of temporal bone, condensation of mesenchyme (mesoderm)

29
Q

Where do ossicles come from?

A

NCC-derived, covered in endoderm

30
Q

What muscle inserts onto the malleus and prevents loud sound from damaging ear? What is it innervated by?

A

Tensor tympani, trigeminal n (first arch mesoderm)

31
Q

What muscle inserts on the stapes and prevents damage from loud sound? What is it innervated by?

A

Stapedius m, facial n (second arch mesoderm)

32
Q

What causes congenital deafness?

A

Maldevelopment of sound-conduction apparatus in middle/external ears (ex: ossicles), neurosensory sensory structures of inner ear, infections