Ear Ii

Front 1

What bone is important for ear formation?

Back 1

Temporal - houses the inner/middle ears and bony portion of outer meatus.

Front 2

4 Parts of Temporal bone:

Back 2

Petromastoid
Styloid process
Squamous portion
Tympanic portion

Front 3

What does the petromastoid portion develop from?

Back 3

Otic capsule of the Chondrocranium

Front 4

What does the styloid process develop from?

Back 4

Pharyngeal arch 2 - Cartilage

Front 5

What does the squamous portion develop from?

Back 5

Pharyngeal arch 1 - Maxillary process

Front 6

What does the Tympanic portion develop from?

Back 6

Pharyngeal arch 1 - Maxillary process

Front 7

How do the petromastoid and styloid process ossify?

Back 7

Endochondrially

Front 8

How do the Squamous portion and Tympanic portion ossify?

Back 8

Intramembranously

Front 9

What does the Aurical develop from?

Back 9

Auricular Hillocks - hills on either side of the first pharyngeal cleft.

Front 10

What pharyngeal arches contribute the auricular hillocks? What structures?

Back 10

1 - tragus, part of helix

2 - remainder of auricle

Front 11

When does the auricle reach its final position?

Back 11

in the fetal period

Front 12

What are the 2 portions of the External Auditory Meatus that must develop?

Back 12

1. Cartilagenous portion
2. Osseous portion

Front 13

What is the cartilagenous portion derived from?

Back 13

1st pharyngeal cleft

Front 14

What is the osseous portion derived from?

Back 14

Medial extension of 1st pharyngeal cleft - MEATAL PLUG

Front 15

What happens to the meatal plug?

Back 15

It develops a lumen and extends; medial end flattens to form the Meatal Plate.

Front 16

What is the Meatal plate?

Back 16

Outer surface of the eardrum.

Front 17

What structures need to be formed to make the middle ear?

Back 17

-Tympanic cavity
-Auditory tube
-Ossicles
-Internal covering of tymp memb

Front 18

How does the Tympanic Cavity form?

Back 18

By lateral evagination of pharyngeal pouch 1 - this forms the Tubotympanic recess

Front 19

What does the Tubotympanic recess form?

Back 19

Epithelial lining of Middle Ear and Auditory tube.

Front 20

What arches are the Ossicles derived from?

Back 20

Arch 1 = malleus and incus

Arch 2 = stapes

Front 21

What is the Tympanic Membrane derived from?

Back 21

The First Closing Plate (interface of cleft/pouch)

Front 22

What composes the Tymp membrane?
-Epidermis
-Fibrous CT
-Mucosal inner layer

Back 22

Epidermis = meatal plug (ecto)
Fibrous CT= 1st arch mesenchyme
(probably neural crest)
Mucosal layer = endoderm tubotympanic recess

Front 23

What size is the middle ear at birth?

Back 23

Adult size!

Front 24

What is the inner ear derived from?

Back 24

the Otic Vesicle

Front 25

What causes the otic vesicle to form?

Back 25

Ectodermal thickening adjacent to the Rhombencephalon forms - Otic Placode

Front 26

What does the Otic Placode become?

Back 26

Otic Pit that disconnects from surface ectoderm and becomes the Otic Vesicle

Front 27

What does the Otic Vesicle send signals to around it?

Back 27

Periotic mesenchyme - and it sends reciprocal msgs to the otic vesicle.

Front 28

What is the otic vesicle induced to do via reciprocal msgs?

Back 28

Form parts of the membranous labrynth

Front 29

What is the periotic mesenchyme induced to do?

Back 29

Condense and form the otic capsule

Front 30

What does the Otic capsule become?

Back 30

Petrous part of the temporal bone.

Front 31

So what develops from the otic vesicle?

Back 31

-Membranous labrynth
-Cranial nerve 8

Front 32

What develops from periotic mesenchym?

Back 32

Osseous labyrinth - petrous part of the temporal bone

Front 33

What does the otic vesicle divide into? (3 things)

Back 33

1. Endolymphatic appendage
2. Dorsal portion
3. Ventral portion

Front 34

What is the dorsal portion of the otic vesicle?

Back 34

Utricle

Front 35

What develops from the utricle?

Back 35

-Semicircular ducts
-Ampulla
-Crista ampullaris

Front 36

What is crista ampullaris for?

Back 36

Sensory of fluid movement in semicircular canals (balance)

Front 37

What is the Ventral portion of the otic vesicle?

Back 37

Saccule

Front 38

What does the saccule develop?

Back 38

-Cochlear duct
-Organ of Corti

Front 39

What is the organ of corti for?

Back 39

Detection of vibration in the cochlea - hearing

Front 40

What is the Macula?

Back 40

The sensory area that develops on the wall of the utricle and saccule.

Front 41

What is anotia/microtia?

Back 41

External ear defect - absent/small auricles

Front 42

What causes auricular tags?
Sinuses?

Back 42

Tags = accesory auricule hillock

Sinus = abnormal 1st cleft devo

Front 43

What is otocephaly? What arch?

Back 43

Low-set ears; associated with a First arch problem

Front 44

What is Meatal atresia caused by?

Back 44

Failure of the meatal plug to canalize

Front 45

What are problems that can develop in the Middle Ear?

Back 45

-Congenital fixn of the stapes
-Defects of Ossicles
-Cholesteatoma

Front 46

What is Cholesteatoma?

Back 46

Benign growth of ENDODERM in tympanic cavity medial to eardrum

Front 47

What is an anomaly of the inner ear?

Back 47

Vestibular Cochlear Dysplasia

Front 48

3 types of Congenital hearing loss:

Back 48

-Conduction
-Sensorineural
-Mixed

Front 49

What percent of all deafness is caused by congenital hearing loss?

Back 49

60%

Front 50

What infection causes congenital hearing loss?

Back 50

Rubella

Front 51

What drugs can cause it?

Back 51

Thaladomide
Acutane