embryology

Question 1

when do the pharyngeal arches develop?

Answer 1

weeks 4 and 5

Question 2

which arch is most cranial?

Answer 2

arch 1

Question 3

how many arches are there?

Answer 3

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

Question 4

what germ layer are the pharyngeal arches from?

Answer 4

all-endo, meso and ectoderm

Question 5

what do the otic placodes give rise to?

Answer 5

inner ear

Question 6

which part of otic vessels gives rise to the cochlea?

Answer 6

saccular

Question 7

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

Answer 7

utricular

Question 8

when do the semicircular canals develop?

Answer 8

week 6

Question 9

internal indentation ?

Answer 9

pouch (endoderm lining)

Question 10

external indentation ?

Answer 10

cleft (ectoderm lining)

Question 11

what are the 2 skeletalcomponents of the first arch?

Answer 11

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

Question 12

what muscles arise from arch 1?

Answer 12

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

Question 13

skeletal components from second arch?

Answer 13

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

Question 14

muscles and nerves from second arch?

Answer 14

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

Question 15

when does cochlea develop?

Answer 15

between week 8 and 8

Question 16

what does the 3rd arch give rise to?

Answer 16

greater horn and lower part of body of hyoid

stylopharyngeus muscles - CN IX supply

Question 17

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

Answer 17

layngeal cartilages

muscles of 4- cricothyroid, levator palatini, pharyngeal constrictiors

muscles of 6- intrinsic layngeal

Question 18

what does the 1st pouch turn into?

Answer 18

middle ear, eustachian tube, tympanic membrane

Question 19

what does the 2nd pouch turn into?

Answer 19

palatine tonsil

Question 20

what does the 3rd pouch turn into?

Answer 20

thymus

inferior parathyroid gland

Question 21

what does the 4th pouch turn into?

Answer 21

superior parathyroid gland and C cells of thyroid

Question 22

what does the 1st cleft turn into?

Answer 22

external auditory meatus

Question 23

what does the 2nd -4thcleft turn into?

Answer 23

they gradullay disappear

Question 24

what is microtis?

Answer 24

small ear

Question 25

how many facial swellings are there?

Answer 25

5

Question 26

when do the facial swelling develop?

Answer 26

from week 4

Question 27

name the 5 facial swellings

Answer 27

frontonasasl prominence maxillary prominence x2 madiubular prominence x2

Question 28

how many nasal swellings are there?

Answer 28

4

Question 29

name the nasal swellings?

Answer 29

medial x2 | lateral x2

Question 30

when do the nasal swellings develop/

Answer 30

week 5

Question 31

where does the nasolacrimal groove lie?

Answer 31

between maxillary prominence and lateral nasal prominance

Question 32

what fuses to for the primary palate?

Answer 32

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

Question 33

what forms the secondary palate?

Answer 33

palatine shelves

Question 34

what form the upper lip?

Answer 34

2 medial nasal prominences and 2 maxillary prominences

Question 35

what forms the lower lip?

Answer 35

mandibular processes

Question 36

what forms the noses bridge and septum?

Answer 36

frontal prominences

Question 37

what forms the noses chest and tip?

Answer 37

medial prominences

Question 38

what forms the alae of the nose?

Answer 38

lateral prominences

Question 39

when do nasal cavities develop?

Answer 39

week 6