BIOMED 3 Flashcards
Craniofacial development + cleft lip & palate (56 cards)
What has developed by 4-5 weeks?
Pharyngeal apparatus
- 1st arch is now called mandibular arch
- 2nd arch is now called hyoid arch
What are 6 external changes that form in weeks 4-5, contributing to craniofacial development?
Frontonasal process
Maxillary process (arches)
Nasal placodes
Nasal pits
Mouth
Tongue
What does the frontonasal process grow from?
Ectomesenchymal cells (cranial neural crest cells left on top from neurulation) that migrate to region & start to form new growth
Why is the frontonasal process an important outgrowth?
Forms structures of the face
Where does the maxillary process (/maxillary arch) start to grow from?
Posterior of mandibular arch
Starts lateral, will move more medially
Why is the maxillary process an important outgrowth?
Forming the palate + bones of the face
How are the nasal placodes and nasal pits formed?
In the frontonasal processes, ectomesenchyme cells form nasal placodes (blue)
Nasal placodes invaginate backwards + medially to form nasal pits (red)
How is the mouth formed?
Buccopharyngeal membrane breaks down (green)
How and when is the tongue formed?
In week 4… tongue buds arise from dif pharyngeal arches (I II III IV)
Fully formed by week 12
What are 4 external changes that form in weeks 5-7, contributing to craniofacial development?
Mandible
Eye placodes
Medial nasal processes fuse
Maxillary process continues to grow
How is the mandible (lower jaw) formed?
Mandibular arches fuse
How do the eye placodes form?
From ectoderm tissues, gives rise to main structures of the eye
What happens when the nasal pits move more medially, closer together?
Medial sides fuse to form tissue called the intermaxillary process (IMP)
What does the intermaxillary process form?
Primary nasal septum
Primary palate
Philtrum
What is the primary nasal septum?
Tissue that remains between the 2 fused medial nasal processes
How can a deviated septum affect speech?
Can affect breathing/resonance of voice
What is the primary palate?
Formed from same tissue as primary nasal septum (IMP) but extends horizontally + posteriorly
What does our palate today derive from?
Fusion of primary + secondary palates
What happens at 5.5 and 6 weeks when the maxillary process continues to grow?
Fuses with lateral nasal process to form nasolacrimal groove (light blue)
Fuses with medial nasal process (red)
Fuses with mandible below (dark blue)
What are 2 external changes that form in weeks 7-8, contributing to craniofacial development?
Philtrum
Fusion of maxillary + mandibular process
What is the filtrum?
Vertical line formed where the medial nasal processes + maxillary processes meet
How does cleft lip occur?
Incomplete fusion of one/both medial nasal processes + maxillary processes
(thus can be uni/bilateral)
What is the term for the incomplete fusion between the maxillary + mandibular processes?
Macrostomia
What is the term for the overcomplete fusion between the maxillary + mandibular processes?
Microstomia (small mouth)