Lesson 3

Question 1

Orofacial structures develop during the _________ week to the _________ week of prenatal development, spanning the later embryonic period and early fetal period.

Answer 1

1. fourth
2. twelfth

Question 2

Define stomodeum

Answer 2

A depression between the brain and the pericardium in an embryo, and is the precursor to the mouth and the anterior lobe of the pituitary gland

Question 3

Describe the palatal development timeline

Answer 3

1. The formation of the palate starts during the fifth week of prenatal development, within the embryonic period.
2. The palate at this time is formed from two separate embryonic structures: primary palate and secondary palate.
3. The palate is then completed later during the twelfth week, within the fetal period.

Question 4

Fifth week of prenatal development the ________ of the primary palate forms

Answer 4

intermaxillary segment

Question 5

The development of the intermaxillary segment from the _________ on the inside of the stomodeum

Answer 5

fused medial nasal processes

Question 6

Describe the location and progression of the Intermaxillary Segment

Answer 6

1. The intermaxillary segment is an internal wedge‑shaped mass that extends inferiorly and deep to the nasal pits on the inside of the stomodeum.
2. It develops into primary palate, the floor of the nasal cavity and the nasal septum.

Question 7

Describe Primary Palate Formation

Answer 7

1. The intermaxillary segment gives rise to the primary palate (or primitive palate).
2. Primary palate will form the premaxillary part of the maxilla, Anterior one third of the final palate, & Part of the hard palate is anterior to the incisive foramen and will contain certain maxillary teeth incisors
3. At this stage of development the primary palate serves only as a partial separation between the developing oral cavity proper and nasal cavity.

Question 8

Describe nasal development in relation to the primary palate

Answer 8

1. Deepening of the nasal pits produces a nasal sac: oronasal membrane
2. Membrane disintegrates: nasal and oral cavities open posterior to developing the primary palate

Question 9

Formation of the _________ completes the first stage of palate development

Answer 9

primary palate

Question 10

Regarding palate formation, during week 6 of prenatal development the bilateral maxillary processes give rise to ________

Answer 10

two palatal shelves (or lateral palatine processes)

Beginning of secondary palate formation

Question 11

Describe secondary palate formation beginning with the formation of the tongue

Answer 11

1. The tongue is forming on the floor of the pharynx, it initially fills the common nasal and oral cavity
2. The palatal shelves grow inferiorly and deep on the inside of the stomodeum in a vertical direction, along both sides of the developing tongue.
3. As the developing tongue muscles begin to function, the tongue contracts and moves out of the way of these developing palatal shelves (WEEK 8)
4. the shelves move into a horizontal position - now superior to the developing tongue.
5. Next, the two palatal shelves elongate and move medially toward each other, meeting and joining, fusing to form the secondary palate

Question 12

2 horizontal palatal shelves grow medially and fuse to form the ___________

Answer 12

secondary palate

Question 13

Growth of the fused medial nasal process from weeks 9-12 result in the formation of the ___________

Answer 13

nasal septum

Question 14

Describe the completion of the palate during week 12

Answer 14

The posterior part of the primary palate meets the secondary palate, and gradually fuses together in an anterior to posterior direction.

Question 15

What does the secondary palate form?

Answer 15

1. The posterior two thirds of the hard palate, which contains certain anterior maxillary teeth (canines) and posterior teeth, posterior to the incisive foramen
2. The median palatine raphe on the surface of the mucosa and underneath, the median palatine suture on the adult bone, indicates the line of fusion of the palatal shelves.

Question 16

Describe Epstein’s Pearl

Answer 16

1. The small white papule seen in the midline of the palate of this infant is an Epstein’s pearl.
2. It represents epithelial tissue that becomes trapped during the palatal fusion.

Question 17

What is a cleft uvula (or bifid uvula)?

Answer 17

1. Uvula forms in 2 sections - does not fuse
2. It is the least complicated example of cleft palate

Question 18

What are the possible disabilities resulting from a cleft palate/lip?

Answer 18

1. Bilateral cleft of the posterior palate - palate open to nasal cavity
2. Complete unilateral cleft of the lip and alveolar process of the maxilla with a unilateral cleft of the primary palate - AKA cleft through lip and anterior portion of palate
3. Complete bilateral cleft of the lip and alveolar process with bilateral cleft of the primary palate - AKA same as above but on both sides
4. Complete bilateral cleft of the lip and alveolar process with complete bilateral cleft of the primary and secondary palatal portions - AKA a combo of the above 3

Question 19

Describe the epidemiology of oral clefts

Answer 19

1. Orofacial clefts are the second most congenital defect.
2. Approximately 1 case of orofacial cleft occurs in every 700 births.
3. 2X higher incidence in males than females.
4. 300 identifiable syndromes are associated with oral clefting.
5. Unilateral cleft lip and palate > higher incidence than bilateral cleft lip and palate (3:1)
6. Males: higher incidence of cleft lip and cleft lip with cleft palate >than females
7. Females: higher incidence of isolated cleft palate >than males

Question 20

What are the risk factors for Oral Clefts?

Answer 20

1. Genetic factors - Identical twin with cleft lip 400X more likely; Sibling with a cleft lip 30X more likely
2. Environmental Factors - Smoking, Alcohol ingestion, Increased parental age

Question 21

The nasal cavity forms in the same time frame as the palate, from the __________ week of prenatal development and will serve as part of the _________ system.

Answer 21

1. fifth to twelfth
2. respiratory

Question 22

Describe Nasal Cavity and Septum Development

Answer 22

1. The future nasal septum of the nasal cavity is also developing when the palate is forming.
2. The structure of the nasal septum, similar to the primary palate, is a growth from the fused medial nasal processes.
3. The tissues that form the nasal septum will grow inferiorly and deep to the medial nasal processes and superior to the stomodeum.
4. The vertical nasal septum then fuses with the horizontally oriented final palate after it has formed.

Question 23

Describe Deviated Septum

Answer 23

1. A deviated septum occurs when the thin wall that makes up the nasal septum inside the nose is displaced to one side.
2. The nasal septum separates the right and left nasal cavities and ideally is situated in the center of the nose, equally separating the two sides.

Question 24

The tongue develops during the ___________ to __________ week of prenatal development. It develops from independent swellings located internally on the floor of the primitive pharynx, formed by the ___________ branchial arches.

Answer 24

1. fourth
2. eighth
3. first four

Question 25

During the 4th week, the single __________ is located in the midline, on the floor of the primitive pharynx

Answer 25

1. Tuberculum impar

Question 26

During the 6th week, two oval __________ (from 1st branchial arch) develop on each side of the tuberculum impar. These will grow in size and merge with each other

Answer 26

lateral lingual swellings

Question 27

The two fused swellings (lateral lingual swellings) overgrow and encompass the disappearing tuberculum impar to form the
____________, which lies within the oral cavity proper.

Answer 27

anterior two thirds, or body of the tongue

Question 28

The ____________ is a superficial demarcation of the line of fusion of the two lateral lingual swellings (as well as of a deeper fibrous structure).

Answer 28

median lingual sulcus

Question 29

Describe the formation of the base of the tongue

Answer 29

1. Posterior to the fused anterior swellings
2. A pair of swellings, called the copula
3. Fusion of mesenchyme of the 3rd & 4th branchial arches
4. The copula gradually overgrows the second branchial arch, or hyoid arch to form the base of the tongue, or posterior one-third.

Question 30

The 4th branchial arch develop the __________

Answer 30

the most posterior region of the tongue and future epiglottis - called the epiglottic swellings

Question 31

Describe the completion of tongue formation

Answer 31

1. As the tongue develops still further, the copula of the tongue base, merges with the anterior swellings of the first branchial arch of the tongue body during the eighth week of prenatal development.
2. This fusion is superficially demarcated by the sulcus terminalis in the mature dorsal surface of the tongue, an inverted V‑shaped groove marking the border between the base of the tongue and its body.

Question 32

List the common Developmental Disturbances of the Tongue

Answer 32

1. Ankyloglossia “tongue‑tied,” which results from a short attachment of the lingual frenum that extends to the tongue apex
2. Bifid tongue