Face, Palate, Pharyngeal Arches

Question 1

When does the stomodeum open up? What happens to the nasal placodes and lens placodes?

Answer 1

During 5th week. Nasal placodes move anteriorly, lens placodes move posteriorly.

Question 2

When does the nasolacrimal groove form, and what does it become?

Answer 2

forms during week 5. Becomes the nasolacrimal duct.

Question 3

Failure of what to fuse during week 6 results in a cleft lip?

Answer 3

Medial nasal prominences, and the maxillary prominence.

Question 4

When is the most critical period of palatogenesis?

Answer 4

Between weeks 6 and 9

Question 5

What does the primary palate originate from?

Secondary palate?

Answer 5

Primary- from the intermaxillary segment (made of the medial nasal prominences)
secondary- from two outgrowths of the maxillary prominences.

Question 6

nasal sac is the primoridial…

Answer 6

nasal cavity

Question 7

What is a cleft palate? What is missing?

Answer 7

Nothing separating the oral and nasal cavities. there is no secondary palate.

Question 8

filtrum is created by the fusion of?

Answer 8

the medial nasal prominences, and the maxillary prominence.

Question 9

dysraphic conditions: What is cranioschisis?

Answer 9

failure of cranial closure

Question 10

dysraphic conditions: what is anancephaly?

Answer 10

no brain

Question 11

dysraphic conditions: what is acrania?

Answer 11

no skull

Question 12

scaphocephaly?

Answer 12

early closure of sagittal suture

Question 13

acrocephaly?

Answer 13

early closure of coronal suture

Question 14

trigonocephaly?

Answer 14

early closure of metopic suture.

Question 15

lower lip and jaw are formed by?

Answer 15

end of 4th week

Question 16

buccopharyngeal fascia is composed of?

Answer 16

endoderm and ectoderm.

Question 17

neural crest mesenchyme invades the arches, and becomes?

Answer 17

skeletal derivatives.

Question 18

1st arch, meckel’s cartilage, becomes what?

Answer 18

mandible, malleus, incus (and ant. malleus ligament, sphenomandibular ligament)

Question 19

2nd arch, Reichert’s cartilage, becomes what?

Answer 19

stapes, styloid process (and upper half of hyoid, lesser horn of hyoid)

Question 20

3rd arch becomes what? bones

Answer 20

greater horn of hyoid, lower half of hyoid

Question 21

4th-6th arches become what? bones

Answer 21

thyroid and cricoid carilages

Question 22

The carilages of arches 1-3 are derived from?

Answer 22

neural crest mesenchyme

Question 23

hypopharyngeal eminence becomes?

Answer 23

epiglottis

Question 24

1st arch gives rise to which muscles? associated nerve?

Answer 24

CN V3

1. masticator muscles
2. mylohyoid
3. anterior belly of digastric
4. tensor palatini
5. tensor tympani

Question 25

2nd arch gives rise to which muscles? associaed nerve?

Answer 25

CN VII

1. mm of facial expression, scalp and ear
2. platysma
3. stylohyoid
4. stapedius
5. post belly of digastric

Question 26

3rd arch gives rise to which mm? associated nerve?

Answer 26

CN IX

1. stylopharyngeus

Question 27

4th arch gives rise to which mm? associated nerve?

Answer 27

CN X- superior laryngeal br

1. cricothyroid

Question 28

6th arch gives rise to which mm? associated nerve?

Answer 28

CN X- recurrent/inferior laryngeal

1. pharynx mm, except stylopharyngeus
2. larynx mm except cricothyroid
3. soft palate mm except tensor palatini
4. striated esophageal mm

Question 29

Pharyngeal pouches are?

Answer 29

endodermal invaginations of the pharyngeal arches

Question 30

What comes from the 1st pouch-tubotympanic recess? (between 1st and 2nd arches)

Answer 30

auditory tube, middle ear, mastoid air cells

Question 31

What comes from the 2nd pouch? (between 2nd and 3rd arches)

Answer 31

tonsils and tonsilar sinus

Question 32

What comes from the 3rd pouch? (between 3rd and 4th arches)

Answer 32

thymus and inferior parathyroids

Question 33

What comes from the 4th pouch? (between 4th and 6th arches)

Answer 33

superior parathyroids, c-cells of thyroid (produce calcitonin),

Question 34

parathyroids III are which ones?

Answer 34

inferior parathyroids

Question 35

Parathyroids IV are which ones?

Answer 35

superior parathyroids

Question 36

1st pharyngeal groove become?

Answer 36

external auditory meatus

Question 37

What is micrognathia and what causes it?

Answer 37

Underdeveloped mandible, 1st arch syndrome

Question 38

What is macrostomia and what causes it?

Answer 38

wide mouth, 1st arch syndrome