Pharyngeal Arches

Question 1

What type of cells are the PA derived from?

Answer 1

Mesenchyme

Question 2

Early in the 4th week, how much of the embryo does the H and N represent?

Answer 2

Half

Question 3

What cell lineage do P pouches come from?

Answer 3

Endoderm

Question 4

What do the P pouches dev into?

Answer 4

Middle ear, parathyroid glands, thymus and palatine tonsils

Question 5

Where does the pharynx extend from/to?

Answer 5

Base of skull to inf boarder of cricoid cartilage of the larynx

Question 6

Which type of cells are critical to the dev of the H and N?

Answer 6

Neural crest cells

Question 7

What does each PA consist of?

Answer 7

Cranial nerve, artery, cartilaginous bar

Question 8

What thickens to fold and create the neural tube?

Answer 8

Overlying ectoderm

Question 9

Ant NT forms the forebrain, midbrain, hindbrain. What are each vesicle stage known as?

Answer 9

Prosencephalon, mesencephalon, rhombencephalon

Question 10

What are the nerves of the PA?

Answer 10

5 (trigeminal), 7 (facial), 9 (glossopharyngeal), 10 (vagus)

Question 11

What is the facial skeleton derived from?

Answer 11

FNP and 1st PA

Question 12

Which arch are the muscles of mastication and facial expression derived from?

Answer 12

1st PA and 2nd PA respectively

Question 13

Which muscle is derived from the 3rd PA?

Answer 13

Stylopharyngeus

Question 14

Which muscles are derived from the 4th PA?

Answer 14

Cricothyroid, levator palatini, constrictors of the pharynx

Question 15

Which muscles are derived from PA 6?

Answer 15

Intrinsic muscles of the larynx

Question 16

Which PA does the trigeminal nerve come from?

Answer 16

1st

Question 17

Which PA does the facial nerve come from?

Answer 17

2nd

Question 18

Which PA does the glossopharyngeal nerve come from?

Answer 18

3rd

Question 19

Which PA’s do parts of the vagus nerve come from?

Answer 19

4th- sup laryngeal, 6th- recurrent laryngeal

Question 20

What are the neural crest- derived cartilage bars for PA 1 and 2 called? What do they both create?

Answer 20

PA1- Meckel’s- maxillary and mandibular prominences, malleus, incus
PA2- Reichert’s- middle ear (stapes), styloid process, hyoid bone

Question 21

What do the PA cartilage bars of PA 4 and 6 create?

Answer 21

Cartilages of the larynx

Question 22

What happens to the first and second aortic arches?

Answer 22

They disappear

Question 23

What does the 3rd aortic arch form?

Answer 23

ICA

Question 24

What does the 4th aortic arch form?

Answer 24

L- arch of aorta, R- brachocephalic

Question 25

What does the 6th aortic arch form?

Answer 25

Pulmonary arch

Question 26

What is on the dame side as the PA’s, pouches of clefts?

Answer 26

Clefts, pouches are on the opposite side

Question 27

What does the 2nd P pouch form?

Answer 27

Palatine tonsil

Question 28

Which pouches form the parathyroid glands?

Answer 28

3rd and 4th dorsal

Question 29

Which P pouch forms the thymus?

Answer 29

3rd arch- ventral

Question 30

Where are the tympanic cavity and ET derived from?

Answer 30

1st P pouch

Question 31

Which is the only P cleft that remains? Why? What can remnans cause?

Answer 31

1st- the second grows down and obliterates the rest. If cervical sinus not obliterated, remnants can lead to cysts/ fistulaes anywhere along ant boarder of SCM