Lecture 15: Ear Development Flashcards Preview

Year 1: 05. Neuro Exam 1 > Lecture 15: Ear Development > Flashcards

Flashcards in Lecture 15: Ear Development Deck (37)
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1

When is the critical period for embryological development of the ear?

Weeks 4-8

2

When does development of the ear occur?

Week 4-20

3

What is found in the external, middle, and inner ear?

External Ear

  • Auricle
  • External Acoustic Meatus
  • External Layer of Tympanic Membrane

Middle Ear

  • Auditory Ossicles (3)
  • Internal Layer of Tympanic Membrane
  • Middle Ear Cavity

Inner Ear

  • Vestibulocochlear Organ
  • Develops separately from external and internal ear

4

The medial part of the external ear came from what pharyngeal arch?

1st Pharyngeal Arch

5

The lateral part of the external ear came from what pharyngeal arch?

2nd Pharyngeal Arch

6

The mesenchymal swellings located within the pharyngeal arches are known as what?

Auricular Hillocks

7

What are the cells that migrate and pull the surface ectoderm around to form the external ear?

Neural crest cells of the auricular hillocks

8

Auricular skin tags that may contain cartilage are a result of what?

Abnormal migration of surface ectoderm and neural crest cells

9

Abnormal or absent migration of the NCCs and auricular hillocks can result in what disorders?

Anotia

Microtia

10

What embryonic layer does the meatal plug arise from?

Surface ectoderm

1st Pharyngeal Cleft

11

What embryonic layer forms the tubotympanic recess?

Endoderm: 1st Pharyngeal Pouch

12

What embryonic layer does the inner ear arise from?

Surface ectoderm

13

How does the inner ear form from surface ectoderm?

  1. Otic Placode thickens
  2. Invaginates to form Otic Pit
  3. Becomes Otic Vesicle that migrates to the head 

14

What embryonic structure gives rise to the membranous labyrinth?

Otic vesicle

Also Surface Ectoderm

15

What does the dorsal side of the otocyst give rise to?

Utricle

  1. Endolymphatic duct and sac
  2. Semicircular ducts and ampullae
  3. Macula of utricle

 

16

What does the ventral side of the otocyst give rise to?

Saccule

  1. Cochlear duct
  2. Ductus reuniens
  3. Maccula of saccule
  4. Organ of Corti

17

What structure connects the cochlea to the vestibular apparatus?

Ductus reunions

18

What is the embryonic layer that gives rise to the hair cells of the inner ear?

Surface ectoderm

19

Where are hair cells located in the inner ear?

What does the respective hair cells sense?

  • Ampullae of Semicircular Canals
    • Rotational Acceleration
  • Macula of utricle and saccule
    • Linear Acceleration 
  • Organ of Corti (cochlea)
    • Sound Vibration 

20

What nerve is responsible for innervation to the inner ear?

Where did this nerve come from?

CN VIII: Vestibulocochlear Nerve

Otic Placode

21

What are the embryonic contributions to the vestibular ganglion?

What cell bodies contribute to this?

Neural crest cells and surface ectoderm

Cell bodies from macula and ampullae 

22

What is the embryonic contribution to the spiral (cochlear ganglion)?

Surface ectoderm

23

What structures does the perilymphatic duct provide passage between?

Subarachnoid space to inner ear

24

What is the ion content of perilymph?

High Na+

Low K+ and Protein

(Similar to CSF)

25

What is the ion content of endolymph?

High K+ and Protien

Low Na+

(Similar to ICF)

26

What produces endolymph?

Stria Vascularis 

27

What embryonic layer does the bony labyrinth arise from?

Mesoderm

Condensation of Mesenchyme 

28

What are the vacuoles of the bony labyrinth?

Scala Vestibuli

Scala Tympani

Semicircular Ducts (Perilymphatic Space)

29

What suspends the cochlear duct within the bony labyrinth and attaches it to the wall?

Spiral Ligament

30

What bones of the middle ear arise from the 1st pharyngeal arch?

What is their embryonic origin?

Malleus and Incus

Neural Crest Cells