Development of Orofacial structures

Question 1

What are the 2 categories of bones in the brain?

Answer 1

Neurocranium and Viscerocranium (facial bones)

Question 2

What cell type produces the neurocranium and viscerocranium?

Answer 2

Mesenchyme (from NCC)

Question 3

What are the 2 types of bone formation?

Answer 3

Intramembranous ossificiation (from mesenchyme) and Endochondral ossification (from cartilage)

Question 4

What bones in the neurocranium are formed via endochondral ossification?

Answer 4

Occipital bone, body of sphenoid, ethmoid and parts of the temporal bone

Question 5

What bones in the neurocranium are formed via intramembranous ossification?

Answer 5

Frontal and parietal bones

Question 6

Frontal bone + parietal bones =

Answer 6

Calvaria

Question 7

What connects bones in the neurocranium that are formed via intramembranous ossification?

Answer 7

SUTURES

Question 8

What bones in the viscerocranium are formed from endochondral ossification?

Answer 8

PA bones – malleus, incus, stapes, styloid process, lesser and greater horns of hyoid

Question 9

What bones in viscerocranium are formed from intramembranous ossification?

Answer 9

Within maxillary prominence: Squamous part of temporal, maxilla and zygomatic bones
Within mandibular prominence: mandible

Question 10

What bones formed from mesenchyme in the viscerocranium becomes part of neurocranium?

Answer 10

Squamous part of temporal bone

Question 11

Bones in babies skulls join too early; as the brain grows the skull deforms to allow growth in certain areas not fused

Answer 11

Craniosynostosis

Question 12

What are the types of craniosynostosis?

Answer 12

Scaphocephaly, brachycephaly, plagiocephaly, trigonocephaly

Question 13

Scaphocephaly

Answer 13

Premature closure of sagittal suture = skull to be long, narrow

Question 14

Brachycephaly

Answer 14

Premature closure of coronal suture = high, tower like skull

Question 15

Plagiocephaly

Answer 15

Premature closure of coronal or lambdoid sutures on one side = skull is twisted and asymmetric

Question 16

Trigonocephaly

Answer 16

Premature closure of metopic (frontal) suture = frontal and occipital bones are malformed

Question 17

What are the facial primordia and when do they appear?

Answer 17

Frontonasal prominence, 2 maxillary prominences and 2 mandibular prominences that appear during 4th week

Question 18

Where do the maxillary and mandibular prominences come from?

Answer 18

PA 1

Question 19

What separates the prominences from the cavity of primordial pharynx?

Answer 19

Oropharyngeal membrane

Question 20

When does the oropharyngeal membrane rupture?

Answer 20

Day 26

Question 21

Where do the facial primordia arise?

Answer 21

Around the stomodeum (opening of mouth)

Question 22

What facial primordia grows first and where are they growing?

Answer 22

Mandibular prominence (MDP), all grow toward midline and towards each other

Question 23

Bilateral oval thickenings of surface ectoderm on inferolateral portion of FNP

Answer 23

Nasal placodes

Question 24

What is created when the placodal edges of the nasal placode proliferate?

Answer 24

Medial and lateral nasal prominences

Question 25

What is formed between the MNP and LNP?

Answer 25

Nasal pit

Question 26

What does the nasal pit go on to form?

Answer 26

Nostrils and nasal cavities

Question 27

When do the facial primordia start to move?

Answer 27

End of 4th week, after day 26 when the oropharyngeal membrane ruptures

Question 28

What separates the maxillary prominence and the lateral nasal prominence?

Answer 28

Nasolacrimal groove

Question 29

When the MXP grow toward each other what happens?

Answer 29

The medial nasal prominences also grow toward each other with the MXPs

Question 30

when do the MNPs start to grow toward the midline?

Answer 30

End of 6th week

Question 31

Once the medial nasal prominences merge with each other, what is formed?

Answer 31

Intermaxillary segment

Question 32

What does the intermaxillary segment create?

Answer 32

Premaxillary part of maxilla, primary palate, core of philtrum of upper lip

Question 33

What separates the growing nasal sacs from the oral cavity?

Answer 33

Oronasal membrane that will eventually rupture so the cavities will connect

Question 34

How is the palate greated?

Answer 34

Primary palate + secondary palate = palate

Question 35

Primary palate

Answer 35

Median palatine process

Question 36

Secondary palate

Answer 36

Lateral palatine process or Palatal shelf

Question 37

What creates the lateral palatine processes?

Answer 37

MXPs

Question 38

Describe how the palatal shelves/lateral palatine processes grow

Answer 38

They start by extending inferiorly on each side of the tongue, as the mandible grows it pulls the tongue forward and down in the mouth and then the lateral palatine processes flip up horizontally where they fuse

Question 39

Lack of fusion between lateral palatine processes and nasal septum or median palatine process

Answer 39

Cleft palate

Question 40

Lack of fusion between the medial nasal prominence and maxillary prominence

Answer 40

Cleft lip

Question 41

when does the nasal septum fuse with the median and lateral palatine processes?

Answer 41

Weeks 9-12

Question 42

What arch contributes most to tongue development?

Answer 42

PA 1

Question 43

Describe PA 1's contribution to tongue development

Answer 43

One median lingual swelling that gets overgrown by 2 lateral lingual swellings that fuse to create the oral part of the tongue

Question 44

Oral part of the tongue

Answer 44

Anterior 2/3

Question 45

What is mostly overgrown but the PA 2 contribute to the tongue

Answer 45

Copulla

Question 46

What do the PA3 and PA4 contribute to the tongue

Answer 46

Hypopharyngeal eminence

Question 47

Pharyngeal part of tongue

Answer 47

Posterior 1/3

Question 48

Line of fusion between anterior and posterior tongue

Answer 48

Terminal sulcus

Question 49

What nerves supply the anterior tongue?

Answer 49

Lingual (V3), chorda tympani (VII)

Question 50

What nerves supply the posterior tongue?

Answer 50

IX, X

Question 51

Incomplete fusion of lateral lingual swellings

Answer 51

Glossoschissis

Question 52

Frenulum is short and attached to tip of tongue

Answer 52

Ankyloglossia

Question 53

Excessively large tongue commonly seen in children with down's syndrome

Answer 53

Macroglossia

Question 54

Tiny tongue commonly seen with micrognathia

Answer 54

Microglossia

Question 55

Where does the tongue musculature come from and what nerve supplies them?

Answer 55

Occipital myotomes; CN XII