10: Orofacial Development

Question 1

Two ossification processes involved in cranium development and explain them

Answer 1

Intramembranous ossification: mesenchyme produces bone without cartilage
Endochondral ossification: bone formation occurs using a cartilagenous intermediate

Question 2

Two pats of the cranium and explain them

Answer 2

Neurocranium: bony case that encloses brain
Viscerocranium: bones comprising facial skeleton

Question 3

Five things formed by cartilagenous neurocranium

Answer 3

1. Occipital bone
2. Body of sphenoid
3. Ethmoid bone (these three in order)
4. Temporal bone: petrous and mastoid parts

Question 4

What forms the membranous neurocranium

Answer 4

Head mesenchyme at the sides and top of brain

Question 5

What does the membranous neurocranium form?

Answer 5

Calvaria (frontal and parietal bones)

Question 6

Cartilagenous viscerocranium

Answer 6

NCCs form pharyngeal arches

Question 7

Membranous viscerocranium: three things formed

Answer 7

1. Squamous part of temporal bones
2. Maxillary bone
3. Zygomatic bones

Question 8

What does the mandible form from?

Answer 8

Cells of the mandibular prominence

Question 9

Craniosynostosis

Answer 9

Premature closing of certain sutures

Question 10

Four types of craniosynostosis

Answer 10

1. Scaphocephaly
2. Brachiocephaly
3. Plagiocephaly
4. Trigonocephaly

Question 11

Scaphocephaly

Answer 11

Sagittal suture closes -> cranium long, narrow, and wedge shaped (50% of cases)

Question 12

Brachiocephaly

Answer 12

Coronal suture closes -> high, tower-like cranium (30%)

Question 13

Two types of plagiocephaly and describe them

Answer 13

Posterior plagiocephaly: unilaterally impacts lambdoid suture
Anterior plagiocephaly: unilaterally impacts coronal suture

Question 14

Trigonocephaly

Answer 14

Frontal suture closes -> metopic suture -> malformation of frontal and orbital bones

Question 15

What is mesenchyme doing during 4-8th weeks of development

Answer 15

It contains active growth centers

Question 16

Which portions of the brain NCCs are related to MXPs, MNPs, and the FNP?

Answer 16

MXPs and MNPs: midbrain, hindbrain NCCs

FNP: midbrain, forebrain NCCs

Question 17

Oropharyngeal membrane

Answer 17

A bilaminar membrane that separates the facial primordia from cavity of primordial pharynx

Question 18

When do nasal placodes form by?

Answer 18

End of 4th week

Question 19

What is occurring simultaneously as the mid face is developing?

Answer 19

PA2 is forming facial muscles, PA1 is forming muscles of mastication

Question 20

Critical period of palatogenesis

Answer 20

End of 6th week -> beginning of 9th week

Question 21

Primary palate in palatogenesis

Answer 21

Wedge-shaped mass of mesenchyme, between maxillary prominences

Question 22

What does the primary palate in palatogenesis form?

Answer 22

Pre-maxillary part of maxilla

Question 23

What forms the secondary palate?

Answer 23

Mesenchyme of maxillary prominences

Question 24

Incisive fossa is the persistence of what?

Answer 24

Nasopalatine canal

Question 25

Palatine raphe indicates...?

Answer 25

Indicates line of fusion of the palate

Question 26

What causes cleft lip?

Answer 26

Lack of fusion between MXPs + medial NPs

Question 27

What causes cleft palate?

Answer 27

Lack of fusion between... 1. Lateral palatine process + nasal septum 2. Lateral palatine process + medial palatine process

Question 28

When does the nasal septum fuse with palatine processes?

Answer 28

9th week -12th week

Question 29

Other names for medial and lateral lingual swellings

Answer 29

Medial and lateral tongue buds

Question 30

N to medial and lateral tongue buds / lingual swellings

Answer 30

Medial: lingual branch of V3 Lateral: chorda tympani of CN 7

Question 31

What forms all tongue buds?**

Answer 31

Prolif of mesenchyme in ventromedial parts of PA1

Question 32

sensory N to hypopharyngeal eminence

Answer 32

Branch of CN 12, superior laryngeal branch of CN 10

Question 33

N to intrinsic tongue muscles + to palatoglossus muscle

Answer 33

Intrinsic: CN 12 Palatoglossus: pharyngeal plexus via CN 10

Question 34

Glossoschissis

Answer 34

Incomplete fusion of lateral lingual swellings -> bifid tongue

Question 35

Ankyloglossia

Answer 35

Frenulum is short + extends to top of tongue - tongue tied and trouble eating

Question 36

Macroglossia

Answer 36

Excessively large tongue, often seen in infants with Down syndrome

Question 37

Macroglossia

Answer 37

Abnormally small tongue, usually associated with micrognathia