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Flashcards in embryology Deck (39):
1

when do the pharyngeal arches develop?

weeks 4 and 5

2

which arch is most cranial?

arch 1

3

how many arches are there?

5 (1,2,34,6) number 5 doesnt develop

4

what germ layer are the pharyngeal arches from?

all-endo, meso and ectoderm

5

what do the otic placodes give rise to?

inner ear

6

which part of otic vessels gives rise to the cochlea?

saccular

7

which part of otic vessels gives rise to the semicircular canals?

utricular

8

when do the semicircular canals develop?

week 6

9

internal indentation ?

pouch (endoderm lining)

10

external indentation ?

cleft (ectoderm lining)

11

what are the 2 skeletalcomponents of the first arch?

maxillary process(dorasl portion)and mandibular process(ventral portion)

12

what muscles arise from arch 1?

muscles of mastication, mylohyoid, tensor tympani and tensor palatini (all supplied by CN V3)

13

skeletal components from second arch?

stapes, styloid process and stylohyoid ligament, lesser horn and upper part of body of hyoid

14

muscles and nerves from second arch?

muscles of facial expression, strapedius, stylohyoid.. all supplied by facial nerve

15

when does cochlea develop?

between week 8 and 8

16

what does the 3rd arch give rise to?

greater horn and lower part of body of hyoid

stylopharyngeus muscles - CN IX supply

17

what does the 4th and 6th arch give rise to?

layngeal cartilages

muscles of 4- cricothyroid, levator palatini, pharyngeal constrictiors

muscles of 6- intrinsic layngeal

18

what does the 1st pouch turn into?

middle ear, eustachian tube, tympanic membrane

19

what does the 2nd pouch turn into?

palatine tonsil

20

what does the 3rd pouch turn into?

thymus
inferior parathyroid gland

21

what does the 4th pouch turn into?

superior parathyroid gland and C cells of thyroid

22

what does the 1st cleft turn into?

external auditory meatus

23

what does the 2nd -4thcleft turn into?

they gradullay disappear

24

what is microtis?

small ear

25

how many facial swellings are there?

5

26

when do the facial swelling develop?

from week 4

27

name the 5 facial swellings

frontonasasl prominence
maxillary prominence x2
madiubular prominence x2

28

how many nasal swellings are there?

4

29

name the nasal swellings?

medial x2
lateral x2

30

when do the nasal swellings develop/

week 5

31

where does the nasolacrimal groove lie?

between maxillary prominence and lateral nasal prominance

32

what fuses to for the primary palate?

medial nasal prominences to give intermaxillary segement - the palatal component of this gives the primary palate

33

what forms the secondary palate?

palatine shelves

34

what form the upper lip?

2 medial nasal prominences and 2 maxillary prominences

35

what forms the lower lip?

mandibular processes

36

what forms the noses bridge and septum?

frontal prominences

37

what forms the noses chest and tip?

medial prominences

38

what forms the alae of the nose?

lateral prominences

39

when do nasal cavities develop?

week 6