Term
which molecular signals cuases
outgrowth
patterning
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Definition
outgrowth - FGF
patterning - SHH & WNT |
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Term
what do Hox genes do in arch development?
what carries the HOX genes?
what regulates the HOX genes?
what can deficiency/excess retinoids/retinoic acid cause? |
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Definition
HOX genes regulate patterning of arches.
the HOX genes are carried by crest cells.
SHH regulates HOX genes.
Deficiency/excess Retinoids, Retenoic Acid disrupt migration of crest cells thus get cranio-facial malformation |
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Term
Neurocranium
2 parts?
what type of ossification forms each part?
what is each derived from?
describe the type of bone. |
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Definition
1. neurocranium
intramembranous ossification (form in a membrane/no cartilage)
derived fr somites, neural crest & paraxial mesoderm
membranous bones
2. viscerocranium
endochondrial ossification (cartilage model)
anterior to pituitary derived from neural crest
post to pit from occipital somites
cartilagenous |
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Term
which two arches forms the bones of the face?
what do the neural crest cells provide |
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Definition
the 1st two pharyngeal arches.
neural crest cells provide the mesenchyme needed for ossification of the facial bones |
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Term
what's stomadeum?
what is it composed of initially?
when does it rupture and become something else?
what's the consequence if it doesn't rupture?
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Definition
future mouth
oropharyngeal membrane composed of endoderm internally & ectoderm ouside
rupture at day 26
needed for fetus to swallow amniotic fluid otherwise get polyhydramnios |
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Term
| what's the significance of the trachea & lung bud developing from the gut tube? |
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Definition
| they have the same nerve supply, thus both constrict on ACh from parasympathetic & expand with epi. |
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Term
what amounts of amniotic fluid amount to poly/olio-hydramnios?
what's the risk of poly? |
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Definition
poly > 2000 ml
(premature rupture of membranes due to pressure, early detachment of placenta, umbilical chord prolapse)
olio < 400 ml |
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Term
structure of the arches
composition
contents
where is cleft/pouch |
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Definition
endoderm inside, meso in middle, ecto outside.
each arch has it's own artery/cartilage/nerve
clefts are external, pouches internal |
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Term
| which cranial nerve supply each arch? |
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Definition
1 - trigeminal V
2 - facial VII
3 - glossopharyngeal IX
4 - sup laryngeal branch of vagus X
6 - recurrent branch of vagus X
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Term
what does a cervical cyst come from?
where are they usually found? |
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Definition
the second arch grows over the 2nd, 3rd & 4th clefts thus creating a cyst
they normally go away if not,
usually found along the sternocleidomastoid |
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Term
| what does the first cleft form? |
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Definition
cleft grows toward the pouch
ectoderm - eardrum
endoderm - tubotympanic recess (fr 1st pouch)
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Term
| what does the second pouch form? |
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Definition
palatine tonsils in the tonsillar fossa (2nd pouch)
tonsils act a defense system |
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Term
what causes DiGeorge syndrome?
name the defects |
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Definition
retinoids regulate HOX genes so deficiency/excess disrupt neural crest migration thus craniofacial defects
CATCH 22 -> stands for:
Cardiac defects
Abnormal facies
Thymic hypoplasia (immunodeficiency)
Cleft palate
Hypcalcemia
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Term
| which bones come from pharyngeal arches 1 thru 6 |
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Definition
1 - malleus & incus, maxilla & mandible
2 - stapes
3 - hyoid bone
4 - thyroid cartilage
6 - cricoid cartilage |
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Term
what does 3rd pouch develop into
|
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Definition
thymus & inf parathyroids
parathyroids are pulled down by thymus
if parathyroid don't separate they will end up behind sternum |
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Term
| what does 4th pouch develop into? |
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Definition
| ultomobranchial bodies (parafollicular C-Cells) |
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Term
which arch does tongue develop from?
so what nerve innervate it?
why is the middle ear innervated by the glossopharyngeal nerve?
which arch is the epiglottis from?
so what's the total innervation of tongue?
what about the tongue muscles? |
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Definition
1st arch thus CN V
the 3rd arch (Copula) overgrows the second and connects into the 1st cleft thus the middle ear is innervated by its nerve CN IX
Epiglottis from 4th arch, thus CN X
so tongue innervation is ant 2/3: CN V, posterior 1/3: CN IX, root of tongue: CN X
taste sense comes from 2nd arch CN VII
tongue muscles from occipital somites thus CN XII |
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