EMBRYO: Face, Nose Flashcards
At Week ___, Facial Primordia is established
4
What are the 5 facial primordia
1 frontonasal prominence
2 maxillaary prominences
2 mandibular prominences
The 5 facial primordia develop where?
as bulging prominences around the stomodeum
Where is each facial primordia (week 4) in relation to th estomoedum?
frontonasal is rostral
maxillary is lateral
mandibular is caudal
Skeletal elements of the face are from ____
neural crest cells
Striated muscle, dermis, endothelium of blood vessels in the face develop from ____
paraxial mesoderm
of occipital somites to the tongue
What separates the primitive oral cavity from the development GI tract?
buccopharyngeal membrane/oral membran/oropharyngeal membrane
When does the buccopharyngeal membranedisintegrate?
Early week 5
During the EMBRYONIC PERIOD (weeks 4-8), what major developments occur in the face?
most facial structures develop during weeks 4-8
During FETAL PERIOD, what happens do the cranium?
What affect does this have on the eyes position/
cranium expands to accompany growing brain, causing eyes to shift anteriorly and medially
During FETAL PERIOD, what happens to the ears?
move superiorly
During FETAL PERIOD, what happens to the nose?
becomes more prominent
During FETAL PERIOD, what is the proportion of the face skeleton relative to the rest of the skull?
at first, facial skeleton appears small in comparison to the rest of skull
proportions become more normal when maxilla/mandible grow to allow space for teeth and once we acquire the paranasal sinuses
Nasal placodes appear at week __
4
The nasal placodes are 2 ______ thickenings within the ____ prominence
2 ectodermal thickenings within the frontonasal prominence
Surrounding ___ of the nasal placodes proliferates
mesenchyme
How do the medial and lateral nasal prominences form?
mesenchyme surrounding the nasal placodes proliferates, forming elevations
Mesenchyme surrounding nasal placodes proliferates and forms elevations. What are they
2 medial nasal prominences
2 lateral nasal prominences
Nasal pits can be seen at week __
5
Nasal pits deepen and expand in what direction
dorsally
what part of nasal placode sinks down into underlying mesenchyme creating a depression (forming the nasal pit)
epithelium
Why do nasal pits appear even more sunken in than they are?
because nasal pits begin to deepen simultaneously to the medial/lateral prominences forming
(week 5)
What significant facial developments occur month 2-3?
facial features are more pronounced
eyes move more mredially
ears more superiorly
FIRST OSSIFICATION CENTER OF THE SKULL
The first ossification center of the skull appears during month ___
2-3
What is the oronasal membrane?
membrane separating the nasal cavity from the oral cavity
When does the oronasal membrane rupture?
end of week 6
What happens after the oronasal membrane ruptures at the end of week 6?
after the oronasal membrane has ruptured (week 6), the nasal cavities communicate with the oral cavity
thru the PRIMORDIAL CHOANAE
What ist he primordial choanea?
This is how the oral cavity and the nasal cavities initially communicate with each other after hte rupturing of the oronasal membrane
What establishes the definitive choanea?
the development of the secondary palate establishes the definitive chonae which separates nasal cavity from nasopharynx
Where is the choana found?
at the posterior extent of the nasal cavity
Nasolacrimal groove is seen week __
6
The nasolacrimal groove is a cleft between what 2 prominences
nasolacrimal groove is cleft between
LATERAL NASAL PROMINENCES and MAXILLARY PROMINENCES
When is the nasolacrimal groove lost?
when the lateral nasal prominences and the maxillary prominences fuse together
What happens to the nasolacrimal groove?
It forms a rod and is canalized
When the nasolacrimal groove becomes a rod, what does it do?
it separates from the surface adn then canalizes into the nasolacrimal DUCT
What is happening (in terms of germinal layers) during the formation of the nasolacrimal duct (from the nasolacrimal groove)
ectoderm proliferates into underlying mesenchyme
What is at the superior end of the nasolacrimal duct?
nasolacrimal SAC
a dilation of the nasolacrimal duct
Where is the nasolacrimal sac?
this is a dilation of the nasolacrimal duct
it is found at the superior end of the duct
The inferior end of the nasolacrimal duct opens up into the ____
inferior meatus of the nasal cavity
The nasolacrimal duct runs from __ to the ___
from the orbit to the inferior meatus of the nasal cavity
**this is why our nose runs when you cry
What structure is responsbile for our nose running when we cry?
nasolacrimal duct
because it runs from the orbit to the inferior meatus of the nasal cavity
Mandibular prominence fuse at ____
the midline
Maxillary prominences grow, move medially, compress the nasal prominences at the midline… during week ___
6
How does the growth of the maxillary prominences effect the medial nasal prominences?
WEEK 6 max prominences growth causes medial nasal prominences to compress together and eventually fuse (week 7)
Medial nasal prominences fuse week ___
7
What causes the medial nasal prominences to fuse week 7?
maxillary prominence growth causes medial nasal prominences to compress and fuse week 7
Week 7, medial nasal prominences fuse creating ____
1 intermaxillary segment
What are the components of the intermaxillary segment?
philtrum, premaxillary part of maxilla, 4 incisors and associated gingiva, and primary palate
The intermaxillary segment is formed by what
the fusing of the medial nasal prominences
What are the lateral palatine processes?
mesenchymal outgrowths
they are medial extensions from the maxillary prominences
lateral palatine processes appear at week ___
6
Lateral palatine processes project in what direction at first
inferomedially
Why do lateral palatine processes project inferomedially at first
to make room for the growing tongue
The lateral palatine processes ultimately fuse together to form
the secondary palate
After the tongue is formed, what happens to the lateral palatine processes
they move horizontal and fuse with each other, primary palate and nasal septum
What embryological structures is the hard palate made up of?
primary palate and anterior most part of secondary palate
What embryological structures are the soft palate and uvula made up of?
the most posterior part of the secondary palate
What ossifies/what does not ossify (hard/soft palate)
hard palate ossifies
soft palate does not ossify
Cleft lips/palates are caused by _____
failure of medial nasal prominences to fuse with maxillary prominences
Where do cleft palates/lips occur?
these are ANTERIOR palatal defects
Cleft lips can be ___
unilateral, bilateral, midline
Cleft palates are between ____
primary and secondary palates
