Chapter 5: Orofacial Development Flashcards
What two structures does the palate form from?
primary palate and secondary palate
When is the palate fully completed?
12th week of fetal period
What are the 3 consecutive stages of palate formation
Formation of primary palate
Formation of secondary palate
Completion of final palate
What are the time periods of the 3 palate stages
Primary palate: 5th - 6th week
Secondary Palate: 6th - 12th week
Final palate: 12th week
What palatal structures are involved in the primary palate?
Intermaxillary segment from fused medial nasal processes
What palatal structures are involved in the secondary palate?
Fused palatal shelves from maxillary processes
What palatal structures are involved in the final palate?
Fusion of all three processes
The final palate involves what?
Fusion of swellings or tissue from different surface of the embryo
What forms during the 5th week?
Intermaxillary segment due to fusion of medial nasal processes
Intermaxillary segment aka … (2)
Globular processes
Primary palate (gives rise)
Premaxillary part of the maxilla is also the …
Anterior 1/3rd of the hard palate
What does the anterior 1/3rd of hard palate contain?
Maxillary anterior teeth (incisors)
When does secondary palate formation occur
During 6th week
What happens to maxillary process in week 6
Gives rise to two palatal shelves
Palatal shelves aka..
Lateral palatine processes
Explain how and where palatal shelves grow and develop
Grows inferiorly and vertically inside the stomodeum, along sides of developing tongue
How is the secondary palate formed
When 2 palatal shelves elongate, move medially towards each other and fuse
What is the posterior 2/3rd of the hard palate consists of
Secondary palate
Canines and posterior teeth
What does the secondary palate give rise to?
Posterior 2/3rds of hard palate, soft palate, uvula
What is the median palatine raphe
Line on the palate of maxillary bone that indicates fusion of palatal shelves
What is the median palatine raphe
Line on the palate of maxillary bone that indicates fusion of palatal shelves
What happens after the final palate is formed
Oral cavity becomes completely separated from nasal cavity
How does a cleft palate occur
failure of fusion of palatal shelves with primary palate
What structure develops during the same time frame as the palate
Nasal cavity
What week does the tongue develop
Week 4
How does the tongue begin to develop
Begins as a triangular median swelling
What is the tuberculum impar
Median tongue bud
Median lingual sulcus
Superficial demarcation of line of fusion of two lateral lingual swellings
What does the degeneration of cells around lingual swellings form?
A sulcus
What does the formation of sulcus mean in the tongue development
Body of tongue is freed from the floor of the mouth except for a small attachement
What is the midline lingual frenum
attachment in floor of mouth that attaches the tongue to the floor
What is the copula
Pair of swellings
Becomes posterior 1/3rd of tongue (base of tongue)
Epiglottic swelling marks…
Marks the development of most posterior region of tongue and site of future epiglottis
Sulcus terminalis
inverted V-shape groove on dorsal surface of tongue
Marks the border between the base of tongue and its body
Foramen cecum
beginning of thyroglossal duct
site of development of thyroid gland
What does the thyroglossal duct show
origin of thyroid gland and migration pathway of thyroid gland into the neck region
Where does thyroid gland form
Inferior terminus
What part of the tongue forms during 4th-8th weeks
Body: tuberculum impar and lateral lingual swellings appear
Base: Copula overgrowing second branchial arches
What part of the tongue forms during the 9th week
Completed tongue: merging of anterior swellings of body and copula base
