Embryology of the Head and Neck: The Pharyngeal Apparatus Flashcards
What two cell types form the branchial arch mesenchyme?
neural crest cells & head mesoderm
What is the fate of the cervical sinus?
It goes away (in normal development)
What is DiGeorge Syndrome?
failure of pouches 3 & 4 to form = no thymus or parathyroid glands
What is ankyloglossia?
lingual frenulum is too short (“tongue-tied”)
What happens to branchial arch 1?
divides and forms maxillary and mandibular prominences
What happens to branchial arch 2?
overgrows arches 3 & 4 and the branchial grooves in between -> smooth neck
What happens to branchial arches 3 and 4?
become internalized
What cell type forms the pharyngeal pouches?
endoderm
What cell type forms the branchial grooves?
ectoderm
What happens to branchial groove 1 (between arches 1 & 2)?
becomes external acoustic meatus
What happens to branchial membrane 1 (between groove 1 & pouch 1)?
tympanic membrane
What forms the auricle/pinna of the outer ear?
adjacent parts of arches 1 & 2
What abnormalities can occur if the cervical sinus does not disappear?
branchial cyst
branchial fistula
branchial sinus
What happens to pouch 1?
forms eustachian tubes as well as forms tympanic cavity (envelops the middle ear bones)
What happens to pouch 2?
helps form the palatine tonsil
What happens to pouch 3?
swells, forms bulbous end, buds off, migrates down (farther than pouch 4)
THYMUS
INFERIOR PARATHYROID GLANDS
What happens to pouch 4?
swells, forms bulbous end, buds off, migrates down (not as far as pouch 3)
SUPERIOR PARATHYROID GLANDS
How are the epiglottis, larynx, vocal cords, and tongue buds formed?
Branchial arch mesenchyme migrates under the floor of the pharynx and pushes up swellings.
What cell types form the connective tissue of the tongue?
neural crest cells of branchial arch mesenchyme
What cell types form the muscles of the tongue?
head mesoderm of branchial arch mesenchyme
What do the branchial arch arteries help form?
aortic arch arteries
What does the branchial arch cartilage form?
viscerocranium
What are the first 5 prominences of the primitive face?
frontonasal prominence
2 maxillary prominences
2 mandibular prominences
What are the 4 additional prominences that form the primitive face?
2 medial nasal prominences
2 lateral nasal prominences
How is the intermaxillary segment formed?
fusion of the medial nasal prominences
What forms the lower lip and lower jaw?
mandibular prominences
What forms most of the upper lip, upper jaw, and secondary palate?
maxillary prominences
What forms the intermaxillary segment of the upper lip/jaw as well as the philtrum of the lip and the primary palate?
medial nasal prominences
What forms the sides of the nose?
lateral nasal prominences
What forms the forehead and the superior part of the nose?
frontonasal prominences
What can happen if the maxillary prominences don’t migrate or fuse correctly?
cleft lip or cleft palate
What forms the primitive nasal cavity?
internal extension of the nasal pits
What forms the primary palate?
extensions from the intermaxillary segment (which is formed from the medial nasal prominences)
What forms the secondary palate?
extensions from the maxillary prominences
When do the paranasal sinuses form and what do they allow you to do?
form mostly after birth and allow you to do throat singing
What is located in the primary palate?
incisor teeth
What normally happens with the primary and secondary palate?
they fuse to form the palate
What can happen if the primary and secondary palates don’t fuse correctly?
cleft palate or cleft palate with cleft lip
What structures does the first arch contribute to?
upper and lower jaw palate ear tongue helps form eye (indirectly)
