Ear Development Flashcards

1
Q

What is the critical development period of the ear?

A

Weeks 4-8

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

What are the components 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
3
Q

What are the components of the middle ear?

A

Three Ossicles (Incus, Malleus, Stapes)
Internal layer of Tympanic Membrane
Middle ear cavity

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

What are the components of the inner ear?

A

Vestibulocochlear organ

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

The component of the outer ear is developed from the 1st and 2nd pharyngeal arches.

A

Auricle

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

The Auricle is developed from ________ _______ which are from NCC and are swellings covered with Surface Ectoderm.

A

Auricular Hillocks

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

What innervates the external ear?

A

Great Auricular N.
Auriculotemporal N. (CN V3) – from 1st arch
CN VII – from 2nd arch
Auricular branches (CN X)

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

When skin tags or formed by the ear, this could be the result of what?

A

– The Auricular Hillocks did not migrate properly IF there is NCC (cartilage) within the skin tags.

– The Surface Ectoderm did not migrate properly

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

How is Anotia (no ear) caused?

A

Abnormal migration of NCC, no Auricular Hillocks were formed.

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

How is Microtia (small ear) caused?

A

Abnormal migration of NCC (abnormal migration of Auricular Hillocks).

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

The External Auditory Meatus is formed by what pharyngeal component?

A

1st Pharyngeal Cleft (Groove)

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

The 1st Pharyngeal Cleft (Groove) will meet up with the 1st Pharyngeal Pouch, and this will induce the formation of the…

A

Meatal plug – This closes off the opening until later stages when the cells undergo apoptosis and create the actual External Auditory Meatus.

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

The Tubotympanic Recess, which meets up with the 1st Pharyngeal Cleft to make the meatus, is derived from what pharyngeal component?

A

1st Pharyngeal Pouch

***Becomes Tympanic Cavity

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

The inner ear is developed from what embryological layer?

A

Surface ectoderm

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

In the formation of the inner ear, a new genetic program starts that initiates the thickening of the Surface Ectoderm which forms the _______ _______. This will invaginate and form the _______ _______, which will eventually round up and form the ________ ________.

A

Otic Placode
Otic Pit
Otic Vesicle

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

The inner ear is developed during what week?

A

4th week

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

The Otic Placode, Otic Pit, and Otic Vesicle (all inner ear) form the primordium of…

A

Membranous Labyrinth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

T/F. As the mandibular prominence grows together medially, the ears will rise up to their appropriate spot on the head.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

The Membranous Labyrinth (from Surface Ectoderm) is divided into a ventral and dorsal side. What develops from the dorsal side?

A

Utricle
Endolymphatic Duct and Sac
Semicircular Ducts and Ampullae
Macula of Utricle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

The Membranous Labyrinth (from Surface Ectoderm) is divided into a ventral and dorsal side. What develops from the ventral side?

A
Saccule
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
21
Q

Where are hair cells located in the inner ear?

A

Ampullae
Macula of Utricle and Saccule
Organ of Corti

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Hair cells are derived from what embryological layer?

A

Surface Ectoderm

***Remember, they’re in the inner ear and it is surface ectoderm!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What do the hair cells in the Ampullae detect?

A

Rotational acceleration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What do the hair cells in the Macula of the Utricle and Saccule detect?

A

Gravity and linear acceleration

25
Q

What do the hair cells in the Organ of Corti detect?

A

Sound vibration

26
Q

T/F. Hair cells are easily regenerated, so if damaged they can grow back quickly.

A

False. When hair cells are damaged they don’t come back.

27
Q

There is a Perilymphatic Duct that opens into the Subarachnoid Space. This duct can be reached from the middle ear’s Tympanic Cavity, why can this be bad?

A

If you get a chronic middle ear infection, which is in the Tympanic Cavity, then the infection can get into the Perilymph and reach the Perilymphatic Duct where it can drain into the Subarachnoid Space. This can cause Meningitis!

28
Q

The Membranous Labyrinth has (CANALS/DUCTS) and contains hair cells. It has (PERILYMPH/ENDOLYMPH) inside of it.

A

Ducts

Endolymph

29
Q

The Bony Labyrinth has (CANALS/DUCTS) and is separated from the Membranous Labyrinth via (PERILYMPH/ENDOLYMPH).

A

Canals

Perilymph

30
Q

The inner ear is innervated by which cranial nerve?

A

CN VIII (Vestibulocochlear)

31
Q

CN VIII (Vestibulocochlear) is derived from which embryological layer?

A

Surface Ectoderm

32
Q

CN VIII (Vestibulocochlear) is derived from the Otic Placode (surface ectoderm). The ganglion that form the nerve are…

A

Vestibular Ganglion

Spiral (Cochlear) Ganglion

33
Q

This substance is similar in content to the CSF, has high Na+, low K+ and protein.

A

Perilymph

34
Q

This substance is similar in content to the intracellular fluid, has high K+ and protein and low Na+.

A

Endolymph

35
Q

This endolymph is produced by the…

A

Stria vascularis

36
Q

This is what stores endolymph.

A

Endolymphatic sac

37
Q

This is formed by a condensation of mesenchyme (mostly mesoderm), and there are vacuoles that form within it.

A

Bony Labyrinth

38
Q

The vacuoles in the bony labyrinth give rise to what?

A

Perilymphatic space (Semicircular ducts)
Scala Vestibuli
Scala Tympani

39
Q

This is part of the cochlear duct and is made of surface ectoderm. It is surrounded by mesenchyme and the bony labyrinth. Contains endolymph.

A

Sclera Media

40
Q

These two components of the bony labyrinth hold perilymph.

A

Scala Vestibuli

Scala Tympani

41
Q

There are ligaments made from mesenchyme that stabilize the Organ of Corti. This component is located within these ligaments.

A

Stria Vascularis

***This produces endolymph!

42
Q

Where is the bony labyrinth being formed?

A

Petrous part of Temporal bone

43
Q

The middle ear part of the External Auditory Meatus is made what embryological layer and what pharyngeal component?

A

Surface Ectoderm

1st Pharyngeal Cleft (Groove)

44
Q

In the middle ear, the Tubotympanic Recess is formed from what embryological layer and what pharyngeal component?

A

Endodermal epithelium

1st Pharyngeal Pouch

45
Q

In the middle ear, the Tympanic Membrane is formed from what embryological layer and what pharyngeal component?

A

Surface Ectoderm, Mesoderm, and Endoderm

1st Pharyngeal Membrane

46
Q

In the middle ear, the Malleus, Incus, and Stapes are formed from what embryological layer and what pharyngeal component?

A

Malleus and Incus – NCC and 1st Pharyngeal Arch

Stapes – NCC and 2nd Pharyngeal Arch

47
Q

The ossicles in the middle ear (Malleus, Incus, and Stapes) are covered with what?

A

Endodermal epithelium

48
Q

This muscle of the ear is derived from mesoderm and inserts on the handle of the Malleus. It prevents damage from loud sounds.

A

Tensor Tympani

49
Q

What embryological layer and pharyngeal component is the Tensor Tympani derived from?

A

Mesoderm

1st Pharyngeal Arch

50
Q

What innervates the Tensor Tympani?

A

CN V

***Remember, Tensor Tympani is from 1st pharyngeal arch and so is CN V

51
Q

This muscle is derived from mesoderm and inserts on the neck of the Stapes. It pulls the Stapes posteriorly and tilts its base in the oval window. Prevents damage from loud sound.

A

Stapedius

52
Q

What embryological layer and pharyngeal component is the Stapedius derived from?

A

Mesoderm

2nd Pharyngeal Arch

53
Q

What innervates the Stapedius?

A

CN VII

***Remember, Stapedius is from 2nd pharyngeal arch and so is CN VII

54
Q

This can occur because the inner forms independently from the middle and external ears. It is most often from genetic factors such as:

    • Maldevelopment of sound-conduction apparatus of middle and external ears
    • Neurosensory sensory structures of inner ear
    • Infections
A

Congenital Deafness

55
Q

What are some of the infections that can cause congenital deafness?

A
    • Rubella
    • Cytomegalovirus
    • Toxoplasmosis
    • Syphilis (Treponema pallidum)
    • Zeka
56
Q

What are the maldevelopments of the sound-conduction apparatus of the middle and external ear that can cause congenital deafness?

A
    • First arch syndrome
    • Abnormalities of Malleus and Incus (1st arch – NCC)
    • Congenital fixation of the Stapes (2nd arch – NCC)
57
Q

Contracting this infection during the 7-8th week of development can cause defects of the spiral organ and deafness.

A

Rubella

58
Q

This is the leading cause of congenital sensorineural hearing loss.

A

Cytomegalovirus

***Form of herpes virus