READ ME / 1: Embryology - pharyngeal arches and ear

Question 1

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Question 2

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Question 3

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Question 5

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Question 6

Which embryological structures give rise to the face and neck?

Answer 6

Pharyngeal arches

Question 7

When do the pharyngeal arches develop?

Answer 7

Weeks 4 and 5

Question 8

Which pharyngeal arch doesn’t really develop into anything?

Answer 8

5th pharyngeal arch

Question 9

Which germ layer contributes to the muscles of the face and neck?

Answer 9

Mesoderm

Question 10

Each pharyngeal arch has four components - what are they?

Answer 10

Mesoderm - develops into muscle

Neural crest - develops into skeleton

Cranial nerve

Artery

Question 11

Pharyngeal clefts are found on the (inside / outside) and are lined by ___.

Answer 11

clefts

outside

ectoderm

Question 12

Pharyngeal pouches are found on the (inside / outside) and are lined by ___.

Answer 12

pouches

inside

endoderm

Question 13

Which cranial nerves are associated with pharyngeal pouches

a) 1
b) 2
c) 3
d) 4-6

Answer 13

a) CN V

b) CN VII

c) CN IX

d) CN X

Question 14

Keeping in mind where it’s found, what are the two parts of the 1st pharyngeal arch?

Answer 14

Maxillary part

Mandibular part

Question 15

What are the bones derived from the

a) maxillary
b) mandibular

parts of the 1st pharyngeal arch?

Answer 15

a) Maxilla, zygomatic bone, temporal bone

b) Auditory ossicles (malleus, incus)

Question 16

Which muscles are derived from the 1st pharyngeal arch?

Answer 16

Muscles of mastication

(supplied by V3)

Question 17

Which cranial nerve is derived from the 1st pharyngeal arch?

Answer 17

CN V

Trigeminal nerve and all three divisions

Question 18

Which bones are derived from the 2nd pharyngeal arch?

Answer 18

Stapes

Styloid process of temporal bone

Upper parts of hyoid

Question 19

Which muscles are derived from the 2nd pharyngeal arch?

Answer 19

Muscles of facial expression

Question 20

Which nerve is derived from the 2nd pharyngeal arch?

Answer 20

CN VII

Question 21

Which nerve is derived from the 3rd pharyngeal arch?

Answer 21

CN IX

Question 22

Which pharyngeal cleft is the only one to remain after development?

What does it form?

Answer 22

1st pharyngeal cleft

External acoustic meatus

Question 23

What do the 2nd, 3rd and 4th pharyngeal clefts form before disappearing?

Answer 23

Cervical sinus

Question 24

The 1st pharyngeal pouch forms structures of the ___.

Answer 24

ear

Question 25

The 2nd pharyngeal pouch forms which lymph structure?

Answer 25

**Palatine tonsils**

Question 26

The 3rd pharyngeal pouch forms which two structures?

Answer 26

**_Inferior_ parathyroid glands** **Thymus**

Question 27

The 4th pharyngeal pouch forms which structures?

Answer 27

**Superior parathyroid gland** **C cells of thyroid gland**

Question 28

What is a **placode**?

Answer 28

**Thickened epithelium**

Question 29

From which thickened epithelial structures do the ears arise?

Answer 29

**Otic placodes**

Question 30

Which germ layer are the otic placodes found in?

Answer 30

**Ectoderm**

Question 31

What does the otic placode do to form the inner ear?

Answer 31

**Invaginates** forming a **pit** and then a **vesicle**

Question 32

What parts of the otic vesicle give rise to the a) semicircular canals b) cochlea?

Answer 32

**a) Urticular portion** **b) Saccular portion**

Question 33

The **urticular part** of the otic vesicle gives rise to what?

Answer 33

**Semicircular canals**

Question 34

The saccular part of the otic vesicle gives rise to what?

Answer 34

**Cochlea**

Question 35

Which sense are the semicircular canals important for?

Answer 35

**Balance**

Question 36

What **cranial nerve** supplies the **crista ampullaris** of the semicircular canals? Which **sense** is this structure important for?

Answer 36

**CN VIII** (**Vestibular** part of vestibulocochlear nerve) **Balance**

Question 37

The **Organ of Corti**, found in the cochlea, is lined by hair cells and transmits sound vibrations to the brain as electrical impulses. What are the important cavities found **superior** and **inferior** to the hair cells?

Answer 37

**Scala vestibuli** superiorly **Scala tympani** inferiorly