Embryology of the face, palate and nasal cavities

Question 1

what forms the pharyngeal clefts

Answer 1

ectoderm

Question 2

what forms the pharyngeal pouches

Answer 2

endoderm

Question 3

what forms the pharyngeal arches

Answer 3

mesoderm

Question 4

what does the 1st pharyngeal arch form in the face

Answer 4

maxilla
mandible
zygomatic
temporal (squamous part)

muscles of mastication- masseter, medial and lateral pterygoid, temporal (all supplied by the V3)

Question 5

what does the 2nd pharyngeal arch form in thr face

Answer 5

muscles of facial expression (all facial nerve)

Question 6

what forms the upper and mid face structures

Answer 6

proliferating mesenchyme

Question 7

what nerve supplies the structures from the 1st pharyngeal arch

Answer 7

CN V (trigeminal)

Question 8

what nerve supplies the structures from the 2nd pharyngeal arch

Answer 8

CN VII (facial)

Question 9

what nerve supplies the structures from the 3rd pharyngeal arch

Answer 9

CN IX (glossopharyngeal)

Question 10

what nerve supplies the structures from the 4-6th pharyngeal arches

Answer 10

CN X (vagus)

Question 11

what facial swelling are prominent at week 4

Answer 11

frontonasal (with nasal placodes)
maxillary (x2)
mandibular (x2)

Question 12

what is the stomodeum

Answer 12

the primitive oral cavity

Question 13

what forms the nasal placodes

Answer 13

ectodermal thickenings on the frontonasal prominence

Question 14

what is the nasolacrimal groove

Answer 14

lies between maxillary prominence and lateral nasal prominence formed by canalization

Question 15

when does palate start to form

Answer 15

week 7

Question 16

what forms the upper lip

Answer 16

2 medial nasal prominences

2 maxillary prominences

Question 17

what forms the lower lip

Answer 17

mandibular prominences

Question 18

what forms the nose

Answer 18

frontonasal prominence- bridge and nasal septum

medial nasal prominences- crest and tip

lateral nasal prominences- alae (sides)

Question 19

what forms the primary palate

Answer 19

fusion of medial nasal prominences give intermaxillary segment

Question 20

what is included in the intermaxillary segment

Answer 20

philtrum of upper lip
maxilla with 4 incisor teeth
primary palate

Question 21

what is the incisive foramen

Answer 21

hole at back of primary palate (intermaxillary segment)

Question 22

how do the nasal cavities form

Answer 22

week 4 picodes
becomes pit as 4 additional (medial and lateral) nasal swelling form on the frontonasal prominence at week 5
nasal pit deepen with the forward outgrowth of frontonasal prominence (mesenchyme)

Question 23

what is the nasal fin and what happens to it

Answer 23

connects the intermaxillary segments (late 6th week)

vacuolises and thins to open the developing nasal sac

Question 24

what is the primitive choanae

Answer 24

how the nasal cavities communicate with the oral cavity (is behind the primary palate)

Question 25

where is the definitive choanae

Answer 25

at junction of nasal cavity and pharynx (relocated due to the formation of the secondary palate)

Question 26

how does the secondary palate form

Answer 26

right and left palatal shelves develop parallel to the tongue fuse in central region- expand anteriorly and posteriorly (weeks 7-10)

Question 27

what is a cleft palate

Answer 27

connection between nostril and intermaxillary segment

Question 28

what are the types of cleft palate/ lip

Answer 28

cleft lip bilateral cleft lip (floating philtrum) cleft palate can have nasolacrimal involvement