Chapter 4: Face and Neck Development Flashcards
What are the FIVE major facial processes/prominences (growth centers) that form during the fourth week? What does each process give rise to?
Single frontonasal process - Upper face
Paired maxillary processes - Midface
Paired mandibular processes- Lower face
What is the globular process?
Single process that is formed when the medial nasal processes join together
What does the medial nasal process give rise to?
Middle of nose and septum
Upper lip and philtrum
Anterior of alveolus - 4 maxillary incisors
Primary palate
What is the primary palate also known as? (2)
Premaxilla
Intermaxillary segment
What does the lateral nasal process give rise to?
Lateral walls of right and left nasal cavities
How is the Maxillary process formed?
Outgrowth of first pharyngeal (branchial) arch
What does the maxillary process form?
Upper cheeks, upper lip (except philtrum). maxilla, secondary palate
What does the mandibular process form?
Lower face, lower cheeks, lower lip, mandible
From what branch is the mandibular process formed
from the 1st pharyngeal arch
How is the mandibular process formed?
Meckel’s cartilage joins the 2 mandibular processes at the midline (later replaced by bone)
What is the mandibular symphysis
midline seam where the mandibular bone joins
What happens at the beginning of week 4?
The primitive mouth becomes the stomodeum
When does the oropharyngeal membrane disintegrate?
End of week 4
How does Meckel’s cartilage disappear?
Through intramembranous ossification when the bony mandible forms
What are placodes
Rounded areas of specialized, thickened ectoderm found in locations of developing special sense organs
What are the three sets of placodes that form in the facial area
Lens palcodes
Otic placodes
Nasal placodes
What happens to the nasal placodes
become submerged and form a depression to become the nasal pits
What is the oronasal membrane
separates the stomodeum from the nasal sacs
Briefly explain how the median nasal processes develop
Appear as two crescent-shaped swellings between nasal pits
Briefly explain the lateral nasal processes
Develop from outer crescent-shaped swellings
When does the intermaxillary segment/premaxillary segment develop?
Starts at week 5 and continues to week 7
Describe the maxillary process
Adjacent swellings from increased growth of mandibular arch on each side of stomodeum
What forms during the 6th week?
Upper lips
How does the upper lip form
When each maxillary process fuses with each medial nasal processes on both sides of stomodeum
What contributes to the upper lip
Maxillary processes
What contributes to the philtrum
Two medial nasal processes
How does cleft lip occur
Failure of fusion of maxillary process with medial nasal process
What feature develops parallel to the face from week 4 to fetal period?
Neck development
Branchial grooves are
Outer side of branchial arch; branchial clefts;pharyngeal grooves
Pharyngeal pouches
inner walls/endodermal evaginations
1st branchial arch
Mandibular arch processes; gives rise to maxillary arch
Meckel’s cartilage
2nd branchial arch
Hyoid arch
Reichert cartilage
3rd Branchial arch
formation of parts of hyoid bone and tongue
