Head and Neck Embryology Flashcards
What are the 4 basic components to the pharyngeal apparatus?
arches
clefts
pouches
membranes
What are the three facial prominences?
frontonasal
maxillary
mandibular
What does the pharyngeal apparatus surround?
the developing foregut
How many pairs of arches are there?
5:
1st, 2nd, 3rd, 4th, 6th
What are the arches covered with externally and what are they covered with internally? What’s in the middle?
extoderm externally
mesenchyme in the middle
endoderm internally
How many pairs of clefts are there”
4
1st 2nd, 3rd and 4th
What are the pharyngeal clefts essentially?
they are surface ectoderm invaginations between the pharyngeal arches
How are the pouches different from the clefts?
clefts are external , pouches are internal
the pouches are endoderm lined areas along the lateral walls of the pharyngeal guts, located opposite the pharyngeal clefts
What do the pharyngeal membranes separate?
hte pouches from the clefts
they do NOT break down in humans, so the clefts and pouches don’t communicate ever (like they do in fish)
What are the three general cells types that migrate into the arches as they form?
mesoderm from somites and somitomeres
neural crest cells
nerves
Where does the mesoderm come from for the eye muscle precursors? For the tongue?
eyes - somitomeres
tongue - occipital somites
another term for neural crest cells is…
neuroectoderm
What are the 4 general elements found in each arch?
skeletal
muscular
neural (cranial nerves)
vascular (aortic arch arteries)
Each arch is supplied by a ___ cranial nerve
single
What CN is associated with the 1st arch?
trigeminal
What nerve is associated with the 2nd arch?
facial
What nerve is associated with the 3rd arch?
glossopharyngeal
What nerve is associated with the 4th arch?
vagus (internal branch ofthe superior larygenal)
What nerve is associated with the 6th arch?
vagus nerve (recurrent laryngeal)
What are the derivatibves of the first pharyngeal arch?
maxillary prominence becomes upper jaw
mandibular prominence becomes lower jaw
so you have maxilla, zygomatic bones, squamous part of temporal bone (intramemebranous oss)
malleus, incus (endochondral ossificaiton)
sphenomandibular ligament, sphenoid spine