DEVELOPMENT OF THE FACE, SKULL, and PALATE - SRS

Question 1

Neuro exam one destroyed your class, and the second exam is exponentially more difficult…

Answer 1

Question 2

From what… does the anterior portion of the skull form?

Answer 2

Neural crest

Question 3

From what… does the posterior portion of the skull form?

Answer 3

Paraxial mesoderm

Question 4

What are fontanelles?

Answer 4

Soft spots that allow for growth of skull postnatally.

Question 5

What do fontanelles allow, specifically, to happen during birth?

Answer 5

Allow the calvaria to undergo changes in shape (molding) during birthing

Question 6

What is this? What is it a subtype of? What is the cause?

Answer 6

a. Scaphocephaly, subtype of craniosynostosis
1. Early fusion of sagittal suture.
2. Skull is long (A-P) and narrow (transverse)

Question 7

What is this condition? What is it a subtype of? What causes this?

Answer 7

a. Brachycephaly, a subtype of craniosynostosis
1. Early fusion of coronal suture
2. Skull is short (A-P) and wide (transverse)

Question 8

What are the three paired facial prominences?

Answer 8

Frontonasal prominence

Maxillary prominence

Mandibular prominence

Question 9

What does the frontonasal prominence develop into?

Answer 9

a. Forehead
b. Bridge of nose and nasal septum
c. Medial nasal prominences – apex of nose, philtrum of upper lip
d. Lateral nasal prominences – ala of nose

Question 10

What does the maxillary prominence form?

Answer 10

a. Upper cheek
b. Lateral portions of upper lip

Question 11

Mandibular Prominences contribute to what?

Answer 11

a. Chin, lower cheek region
b. Lower lip
c. Part of external ear

Question 12

What does the upper lip develop from?

Answer 12

medial nasal prominences and maxillary prominences

Question 13

What does the lower lip develop from?

Answer 13

mandibular prominences

Question 14

Nasal placodes (thickening of surface of ectoderm) form on frontonasal prominence and then…

Answer 14

invaginate to form nasal pits

Question 15

Describe the formation of the nose

Answer 15

1. Nasal placodes (thickening of surface ectoderm) form on frontonasal prominence and then invaginate to form nasal pits.
2. Mesenchyme surrounding the margins of the nasal pits proliferates to form the medial and lateral nasal prominences.
   a. Medial nasal prominences are pushed towards midline and will fuse with one another (forming the intermaxillary segment).
   b. The intermaxillary segment will fuse with the adjacent maxillary prominence to form upper lip.

Question 16

What forms the nasolacrimal duct?

Answer 16

1. The maxillary prominence fuses with the lateral nasal prominence along the nasolacrimal groove.
2. The nasolacrimal duct forms from the ectoderm of nasolacrimal groove.

Question 17

What do the olfactory epithelium and CN I develop from?

Answer 17

Develop from nasal sac ectoderm

Question 18

The oronasal membrane ruptures by week 6, and is replaced by what?

Answer 18

palate

Question 19

What are do muscles of mastication develop from? What cranial nerve do they get?

Answer 19

1.Muscles of mastication from first pharyngeal arch (trigeminal n).

Question 20

What forms the muscles of facial expression? What is their innervation?

Answer 20

1.Muscles of facial expression from 2nd pharyngeal arch (facial n).

Question 21

What does the primary palate form from? What does it fuse with above and posteriorly?

Answer 21

Forms from intermaxillary segment

Above: nasal septum

Posteriorly: lateral palatine shelves

Question 22

What does the secondary palate form from?

Answer 22

Lateral palatine shelves form from maxillary prominences.

Question 23

What foramen is the landmark between the primary and secondary palates?

Answer 23

Incisive canal

Question 24

What is the most common craniofacial anomaly?

Answer 24

Clefts of the lip and palate

Question 25

What is the extent of a complete anterior cleft? What is this caused by?

Answer 25

1. A complete anterior cleft extends through the lip, alveolar part of maxilla to incisive fossa, separating primary from secondary palate.
2. Caused by failure of maxillary prominence to fuse with medial nasal prominence (intermaxillary segment).

Question 26

An anterior cleft is anterior to what?

Answer 26

The incisive foramen

Question 27

What is the median cleft due to? Is this common?

Answer 27

Failure of nasal prominences to merge (is rare)

Question 28

What is the posterior cleft posterior to?

Answer 28

Incisive foramen

Question 29

What causes the posterior cleft to form?

Answer 29

a.Lack of fusion of lateral palatine plates causes cleft palate and/or uvula.

Question 30

What is the extent of an oblique facial cleft?

Answer 30

1.Runs from mouth towards eye; results in nasolacrimal duct not being incorporated into face.

Question 31

What causes an oblique facial cleft?

Answer 31

1.Failure of maxillary process to fuse with lateral nasal prominence.

Question 32

What are most craniofacial defects from?

Answer 32

Disruption of neural crest cell migration or differentiation in the face.

Question 33

Describe the cause and extent of an oblique facial cleft.

Per Dr. Funk, this question is on the exam.

Answer 33

Failure of maxillary process to fuse with lateral nasal prominence.

Runs from mouth toward eye, results in nasolacrimal duct not being incorporated into the face.