Embryology: Development of Pharyngeal Arches

Question 1

Face development begins in about the ___ week

Answer 1

4th

Question 2

Palate development begins in about the ___ week

Answer 2

5th

Question 3

At four weeks of development, the human embryo head and neck resebles the gill region of fish. Originally called the branchial (meaning gill) region, now called the pharyngeal region in that it surrounds the ____ where the structures that develop into the upper respiratory and proximal digestive systems are located

Answer 3

foregut

Question 4

The Pharyngeal complex has what 3 principle components?

Answer 4

• CAP (cleft, arch, pouch)
  
  • Pharyngeal arch
    
    • (skeletal muscle, nerve, and artery)
  • Pharyngeal clefts
  • Pharyngeal pouches

Question 5

_____ from the first and second pharyngeal arches migrate into the developing face

Answer 5

neural crest derived mesenchyme

Question 6

What are the components of the head that are derived from neural crest cells

Answer 6

• facial skeleton
• Coronal and sagittal sutures
• anterior portion of sphenoid and the frontal bones

Question 7

Skeletal elements of pharyngeal arch 1

Answer 7

• Migrating neural crest in the first arch induce the formation of a cartilaginous rod (Meckel’s cartilge)
  
  • The more posterior portion differentiates and becomes ossified into the malleus and the incus
  • the more anterior portion of Meckel’s cartilage serves as a scaffolding for intramembranous bone formation of the mandible
  • In between the two middle ear bines and the mandible, the sphenomandibular ligament forms, connecting the first arch skeletal elements.
  • In addition, the maxial, zygoma and part fo the temporal bone form in the maxillary portion of the first arch
  • (note frontonasal region comes from first arch)